comprehensive inorganic chemistry ii || vanadium biochemistry
TRANSCRIPT
Co
3.13 Vanadium BiochemistryDC Crans and PB Chatterjee, Colorado State University, Fort Collins, CO, USA
ã 2013 Elsevier Ltd. All rights reserved.
3.13.1 Introduction 3243.13.2 Vanadium Chemistry 3243.13.3 Enzymes Containing Vanadium 3253.13.3.1 Nature’s Halogenation Catalysts: VHPOs 3253.13.3.1.1 The peroxidase reaction and general description of the haloperoxidase enzymes 3253.13.3.1.2 Vanadium bromoperoxidase 3253.13.3.1.3 Vanadium chloroperoxidase 3263.13.3.1.4 Comparing the haloperoxidases 3273.13.3.1.5 Substrate activity by haloperoxidases 3273.13.3.1.6 Phosphatase activity by haloperoxidases 3293.13.3.2 Nitrogenases 3303.13.3.2.1 General overview 3303.13.3.2.2 Structural perception and amino acid sequence 3303.13.3.2.3 Enzyme catalysis 3313.13.3.2.4 Dinitrogen reduction 3313.13.3.2.5 Carbon monoxide reduction 3323.13.3.3 Vanabins 3323.13.4 Organisms Accumulating Vanadium 3323.13.4.1 Tunicates 3323.13.4.1.1 General overview 3323.13.4.1.2 Oxidation state of vanadium in tunicates 3333.13.4.1.3 Tunichromes 3343.13.4.1.4 Vanadium accumulation and reduction in tunicates 3343.13.4.2 Amavadine 3353.13.4.2.1 General overview 3353.13.4.2.2 Structure and reactivity 3353.13.4.3 Fan Worm 3373.13.5 Insulin Enhancing Effect of Vanadium Compounds 3373.13.6 Conclusion 338Acknowledgments 338References 338
AbbreviationsABTS 2,20-Azino-bis(3-ethylbenzthiazoline-6-sulfonic
acid)
acac Acetylacetonante
ADP Adenosine 50-diphosphateALG Alginates
ATP Adenosine 50-triphosphateCPO Chloroperoxidase
CSA Chemical shield anisotropy
CWEPR Continuous wave electron paramagnetic
resonance
DFT Density functional theory
DNA Deoxyribonucleic acid
DOPA 3-(3,4-Dihydroxyphenyl)alanine
EFG Electric field gradient
EPA Environmental Protection Agency
ESEEM Electron spin-echo envelope modulation
ESR Electron spin resonance
EXAFS Extended x-ray absorption fine structure
FeVco Iron–vanadium cofactor
mprehensive I
norganic Chemistry II http://dx.doi.org/10.1016/B978-0-08-09777H3hida N-Hydroxyiminodiacetate
H3hidpa l,l-N-Hydroxyimino-a,a0-dipropionic acidHase Hydrogenase
HOX Hypohalous acid
IR Infrared
MCD Molar circular dichroism
MMA Methyl mercaptoacetate
MW Molecular weight
NADPH Nicotinamide adenine dinucleotide
phosphate
NHE Normal hydrogen electrode
NMR Nuclear magnetic resonance
PS Phenolic substances
QTAIM Quantum theory of atoms in molecules
SEC Size exclusion chromatography
TFA Trifluoroacetic acid
TOPA 3,4,5-Trihydroxyphenylalanine
UV Ultraviolet
VAP Vanadium-associated proteins
VBPO Vanadium bromoperoxidase
4-4.00324-7
323324 Vanadium Biochemistry
VCPO Vanadium chloroperoxidase
VHPO Vanadium haloperoxidase
VIPO Vanadium iodoperoxidase
VNase Vanadium nitrogenase
XANES X-ray absorption near edge structure
XAS X-ray absorption spectroscopy
H2O
V
H2O
O
O
-O
Scheme 1vanadium(IV
O 2+
OH2V
H2O
1
3 4 5
2
O-
-
V
O
OH
O--O
V
O
OH
OH-O
OH2
3+
OH2H2OV
H2O
OH2
OH2
OH2
Schematic illustration of major aqueous solution species for) (1), vanadium(III) (2) and vanadium(V) (3, 4, 5).
3.13.1 Introduction
Vanadium is a trace metal that, although present in our vitamin
supplements and healthyMt. Fuji ‘Vanadiumwater’ still remains
an element with less certain functions in biology and biochem-
istry. Although some groups are convinced that vanadium is an
essential element for life,1,2 experiments supporting such role are
difficult to come by and are often accompanied by experimental
limitations. The last 50 years have uncovered the rich bio-
chemistry of vanadium with proteins and organisms requiring
this colorful metal for function in the biosphere.3–9 These pro-
teins include the enzymes haloperoxidases in algae and
seaweed,3,4,7,10–17 vanadium-containing nitrogenases,4,18,19
other enzymes such as periplasmic nitrate reductase,20,21 and
the vanadium-binding proteins, vanabins.4,22–25 Vanadium-
containing tunicates,22–26 also referred to as sea squirts, contain
up to molar concentrations of vanadium where vanadium is
associated with the vanabins.4,22–25 Vanadium-accumulating or-
ganisms including the mushroom, Amanita muscaria,27–33,34,35
together with the tunicates contain the highest concentrations
of vanadium. In addition to its role in biochemistry, vanadium
can take on multiple roles such as vanadium(V)’s analogy with
phosphorus4,36 and vanadium(IV)’s analogy with divalent metal
ions4,37,38 and these are different from the proteins and organ-
isms that require vanadium that are described in this chapter.
Vanadium with element number 23 is a first-row transition
metal between titanium and chromium. It is the 22nd most
abundant element in the earth’s crust surpassing important,
bioactive metals such as Cu and Zn.8 Through its presence in
the soil, it enters the food chain through assimilation into the
vegetation and is a common trace element in the seeds and roots
of plants and crops.39 This propagation of vanadium through
the food chain explains the traces of vanadium that commonly
are found in human and animal foods. For example, in a glass of
beer there is approximately 1 mg of vanadium. It exists in a
number of minerals such as carnotite, vanadinite, and titanifer-
ous magnetite, and is particularly common in rock-containing
crust.40,41 It is also an important component of carbiferous
materials such as oils, shales, tar sands, and coals, and is often
released upon processing of fuels40 which will leach into the
ground water. Vanadium is routinely monitored before certify-
ing the purity of drinking water. Environmental Protection
Agengy (EPA) standards for acceptable vanadium levels in
water are 50 mg l�1, but even in areas with vanadium-containing
rocks, the vanadium content in the ground water is lower.40,41
The concentrations of vanadium in vanadium-accumulating
organisms are significantly higher,4,41 although the vanadium
is complexed and thus not toxic. In contrast, algae and lichen
that contain vanadium haloperoxidases (VHPOs) still only sup-
port an overall low level of vanadium despite the production of
the vanadium-containing enzymes. We herein review vanadium
biochemistry with a focus on the biology and biochemistry that
requires vanadium.
3.13.2 Vanadium Chemistry
As a group 5metal ion, vanadiumhas a range of oxidation states
available to it and several of these are represented in its
biochemistry.42,43 In low oxidation state vanadium com-
pounds are not stable in the presence of oxygen (1 and 2,
Scheme 1) and thus generally not compatible with environ-
ments at the surface of the earth.41,44 Vanadium is abundant in
the earth’s crust generally in the highest oxidation states. The
vanadium nucleus has only two natural isotopes, 50V and 51V,
of which the latter has the natural abundancemore than 99%.45
In the biosphere, the most common forms of vanadium are in
oxidation states (IV) and (V).6,42 The forms of vanadium found
in anaerobic environments can be at oxidation state III and thus
in the lower oxidation state range of vanadium.46 The vana-
dium in nitrogenase and tunicates are in oxidation states (III)
and/or (IV) and testify to the anaerobic environment of these
systems.
The vanadium ion in oxidation state (III) is a d2 metal ion
and in oxidation state IV is a d1 metal ion.46 Both vanadium
(III) and (IV) undergo hydrolysis reactions and therefore form
several species.4,27,47 Studies with these oxidation states in
the absence of ligands and/or in the presence of oxygen will
result in oxidation of vanadium. Vanadium(III) chemistry
is less investigated than vanadium(IV) chemistry.46,48,49
However, several species form from this oxidation state
which can be quite stable even in the presence of oxygen.50
In oxidation state (III) vanadium is always non-oxo. In aque-
ous medium, the hexaaquanonoxovanadium(III) forms exclu-
sively (2, Scheme 1). The vanadium(IV) metal ion generally
exists as an oxo ion, VO2þ (1, Scheme 1), and forms the
classical eight-line profile in EPR spectroscopy.37,51 Bare vana-
dium(IV) ion is rare and has been explored relatively little
because of the extreme inertness of the V¼O terminal bond
Vanadium Biochemistry 325
and the unusually high V¼O bond energy in vanadyl com-
pounds. Precursors containing this functionality are common
and include VOSO4 and VO(acac)2.
The coordination geometry of a number of oxovanadium
species ranges between square pyramidal and octahedral.
The axial V¼O bond length is in the range 1.57–1.67 A. The
O–V–O bond angles deviate from the ideal value resulting in
the central vanadium being raised slightly above the basal
plane. Molecular orbital description reported by Ballhausen52
describes the bonding properties in oxovanadium species and
the strong terminal V¼O bond which by some is described as a
V�O bond. Other than one axial s-bond there are two axial p-bonds. As in the ion, the p-bonding orbitals are directed axially
resulting in a triple bond between the two atoms, vanadium,
and oxygen. Vanadium(IV) is stable at low pH, but at neutral
pH requires complexation in order to prevent oxidation.53 The
vanadium(IV) species is versatile by forming stable complexes
with a range of ligands with varying donor sites and
denticity.54 Complexes with O-based donors are particularly
stable and N-based donors are also very common.54 Com-
plexes formed with S-based donors are less common,53,54 but
play an important role in vanadium biochemistry.53
In oxidation state (V), vanadium is a d0 metal ion and, as
such, has complex aqueous chemistry.5,54 This oxidation state
has the metal ion existing in both cationic and anionic forms
and forms a wide range of complexes.5 The coordination
chemistry of vanadium(V) is very well understood, because
the diamagnetic nature of this metal ion and its high natural
abundance and desirable quadrupolar moment render it a
very convenient nuclear magnetic resonance (NMR)-active
nucleus.51,55–59 However, the multiple protonation states and
nuclearities of the oxovanadates that form in aqueous solution
make this chemistry very environment dependent and range from
anions at the higher pH values to cationic forms at the lower pH
values.6,60 In nature, vanadium(V) exists in multiple forms of
oxovanadates (3–5, Scheme 1) in a range of minerals.44 This
oxovanadate(V) chemistry is avoided when vanadium is firmly
complexed to a protein such as observed when vanadium is a
cofactor in haloperoxidases.
3.13.3 Enzymes Containing Vanadium
The largest class of enzymes that naturally contain vanadium is
the haloperoxidases.3 VHPOs catalyze a two-electron oxidation
of halide (X�) to hypohalous acid (HOX) in the presence of
hydrogen peroxide via an activated peroxometal intermediate
(eqn [1]). The reaction does not work for fluoride (F�). During
the oxidation process halogenation of a range of organic sub-
strates takes place.
RHþH2O2 þ X� þHþ ! RX þ 2H2O [1]
The second known family of bacterial and archaeal metal-
loenzymes that contain vanadium is vanadium nitrogenases
(VNases). These enzymes are produced under the condition of
molybdenum depletion and they are responsible for enzymatic
dinitrogen fixation. The reaction depicted in eqn [2] shows
conversion of atmospheric dinitrogen (N2) to bioavailable
ammonia (NH3) with concomitant production of hydrogen
(H2) gas:
N � Nþ 8Hþ þ 16MgATPþ 8e�
! 16MgADPþ 16PiþH2 þ 2NH3 [2]
Vanabins are known as vanadium-binding proteins. Using
a specific antibody, these proteins were shown to be located in
the cytoplasm of vanadocytes (vanadium-containing blood
cells) of the ascidian Ascidia sydneiensis samea. These are the
first proteins reported to show specific binding to vanadium
(IV). The role of the vanabins may include transport and
storage processes in tunicates.
3.13.3.1 Nature’s Halogenation Catalysts: VHPOs
3.13.3.1.1 The peroxidase reaction and generaldescription of the haloperoxidase enzymesThere are three known types of haloperoxidases: two contain
either a prosthetic heme group found in mammals or a
vanadate ion as in the case of VHPOs.10 The third type
of haloperoxidases are metal-free haloperoxidases.61,62 The
vanadium-containing haloperoxidases (VHPOs) can be divided
into chloroperoxidases (VCPOs), bromoperoxidases (VBPOs),
and iodoperoxidases (VIPOs),63 with the proteins being classi-
fied according to the most electronegative halide that they
oxidize. VCPOs oxidize Cl�, Br�, and I� in the presence of
H2O2. VBPOs can oxidize Br� and I� while VIPOs catalyze the
oxidation of I�. Haloperoxidases generate oxygen in the absence
of an organic substrate by the disproportionation of hydrogen
peroxide by halide.64 In the presence of bromide, singlet oxygen
is the product.65 The native enzymes require vanadium(V) in
the form of a vanadate covalently linked to a histidine for their
activity. The function of these enzymes is believed to be the
biosynthesis of halogenated natural products in vivo.14,66
VHPOs selectively halogenate the phenyl group of a number of
antifungal, antibacterial, and antitumor compounds.67 Within
the various families of VHPOs only 20% of the primary amino
acid sequences are preserved, whereas the overall structures of
these proteins were found to be different with the exception
of the regions close to the metal active site.68–70
After Vilter’s discovery of VBPO in 1984 from Ascophyllum
nodosum,10,71 the existence of vanadium as a redox cofactor
in other peroxidases was demonstrated.15 Haloperoxidases
are universally present in all types of marine algae and in
many other marine organisms.10,72 Additionally, they are
found in terrestrial fungi and in some lichen.13,73 All the
VHPOs can survive temperatures up to 70 �C. They also remain
functional in many organic solvents and resistant toward oxi-
dative inactivation in the presence of high concentrations of
peroxide.74 Several reviews describe the various aspects of
VHPOs including enzyme structure, function, mechanism,
and functional and structural model chemistry and the reader
is referred there for more detail.4,10
3.13.3.1.2 Vanadium bromoperoxidaseA number of VBPOs have been isolated from different enzyme
sources,75 but the most explored enzyme is the first reported
120.5-kDa isoenzyme of VBPOs from A. nodosum.69 Studies
have focused on substrate specificity and structural, kinetic,
and spectroscopic properties of VBPO. The coordination envi-
ronment around vanadium and the oxidation state of the
metal was investigated using 51V NMR,6,76 XAS,77 continuous
326 Vanadium Biochemistry
wave electron paramagnetic resonance (CWEPR),78 Electron
spin-echo envelope modulation (ESEEM),79 and x-ray
crystallography.69 The x-ray crystal structure of the VBPO
from the red alga Corallina pilulifera has also been solved in
the presence of phenol red and phloroglucinol.80 In the active
site of VBPOs from A. nodosum, there are two vanadium atoms
per homodimeric structure of the enzyme. X-ray crystallographic
studies at 2.4 A resolution show that the homoenzyme has the
dimension around 90�77�75 A. The two monomeric units
are bridged by three intramolecular and two intermolecular
disulfide bridges.69 The protein fold is mainly a-helical consist-ing of two to four helix bundles and six additional long helices.
The vanadate is bound at the end of a 15 A-deep substrate
funnel. The coordination environment around the vanadium
center is trigonal bipyramidal completed by a NO4 donor set
(Figure 1).69 Carboxylate residues on the protein chains support
the vanadate (VO4) moiety (vanadium(V)) with the His-486
nitrogen atom covalently bound to the vanadate group
(Figure 1). The negative charge on the vanadate is supported
by an extensive hydrogen bond network, which involves differ-
ent protein residues.
3.13.3.1.3 Vanadium chloroperoxidaseThe VCPOs were found in a number of dematiaceous
hyphomycetes,81,82 such as the pathogenic fungus Curvularia
inaequalis.83 The secondary structure of the protein is mainly
all-helical consisting of 2a helices. Of them, two central four-
helix groups are the main structural motifs (mainly a helical).68
The crystal structure of a 67-kDa vanadium-dependent haloper-
oxidase was solved (Figure 2) for the resting state of the native
VCPO at pH 8.0.68,74 The coordination geometry of the vana-
dium is trigonal bipyramidal with three equatorial oxygens and
Asp 278
Asp 490
2.9
2.5
2.7
2.8
2.93.1
3.1
W 773
W 772
W 761His 418
His 411
His 486
Figure 1 Structure of the active site of vanadium bromoperoxidase(VBPO) isolated from the brown alga A. nodosum. Adapted fromWeyand, M.; Hecht, H. J.; Kiess, M.; Liaud, M. F.; Vilter, H.; Schomburg,D. J. Mol. Biol. 1999, 293, 595, with permission. Copyright 1999 Elsevier.
bond distances around 1.65 A. The presumed OH group in one
apical position has a bond length of 1.93 A and the nitrogen
atom from His-496 has a bond length of 1.96 A in the other
apical site (Figure 2). The vanadate-binding site resides at the
bottom of a �10 A solvent-accessible channel. The overall neg-
ative charge on the vanadate is compensated by hydrogen bonds
to several positively charged protein side chains (e.g., Lys-353,
Arg-360, and Arg-490).68 Other important residues including
Lys-353, Arg-360, His-404, and Arg-490 form hydrogen bonds
with the nonprotein oxygens of vanadate (Figure 2). This bond
distance for the apical OH ligand is in the range for vanadium
(V)–hydroxyl bond,84 and its hydrogen bonding with the His-
404 residue suggests the fifth ligand is a hydroxyl group. How-
ever, unambiguous determination of the presence and positions
of hydrogen atoms is difficult. The three equatorial oxygen
atoms also form H-bonds with Ser-402 and Gly-403 of the
enzyme. In the peroxo derivative85 of the enzyme, x-ray crystal-
lography at a resolution 2.24 A reveals that the peroxide is
bound to the vanadium center in an Z2 fashion after the release
of the apical oxygen atom. In this form, the vanadium center is
surrounded by four nonprotein oxygen atoms while the e2nitrogen from His-496 occupying the final coordination site of
the vanadium. The metal cofactor characterized by strongly
distorted trigonal bipyramidal geometry with two peroxo oxy-
gens, an oxo oxygen atom, and the nitrogen atom occupies the
basal position while the other oxo oxygen is in the apical posi-
tion (Figure 3).
Extended x-ray absorption fine structure (EXAFS) for the
native and peroxo forms of VCPO from C. inaequalis at pH
6.0 combined with the crystallographic and kinetic data
suggests side-on-bound peroxide involving V–O bonds of
1.67 and 1.88 A. The weakly bound oxygen would there-
fore be ’activated’ for transfer.86 Messerschmidt et al. have
His-496
His-404
Arg-490
N
O
O
O
O V
Asp-292
Lys-353
Ser-402
Gly-403
Arg-360
Figure 2 Structure of native VCPO isolated from C. inaequalis.Reprinted from Plass, W. Angew. chem. Int. Ed. Engl. 1999, 38, 909, withpermission. Copyright 1999 Wiley-VCH.
Lys 353 N
O
O OV
ON
N
N N
N
Arg 360
1.471 1.8551.601
1.9261.887
His 496Arg 490
2.189
Figure 3 Metal cofactor binding site in the peroxo form of VCPOisolated from the fungus C. inaequalis. Relevant bond distances are in A.Adapted from Zampella, G.; Fantucci, P.; Pecoraro, V. L.; De Gioia, L.J. Am. Chem. Soc. 2005, 127, 953. Copyright 2005 American ChemicalSociety, with permission.
His-404His-418
His-411
His-496His-486
Gly-403
Phe-397
Asp-292
Gly-417
Arg-360Arg-349
Lys-353Lys-341
Ser-402Ser-416
Figure 4 Superposition of VCPO from C. inaequalis (CPK color) andVBPO from A. nodosum (pink) to demonstrate the similar geometriesaround the metal active center. Active site residue labels correspond toVCPO (top) and VBPO (bottom). Adapted from Pooransingh-Margolis,N.; Renirie, R.; Hasan, Z.; Wever, R.; Vega, A. J.; Polenova, T. J. Am.Chem. Soc. 2006, 128, 5190. Copyright 2006 American ChemicalSociety, with permission.
Vanadium Biochemistry 327
determined the crystal structure of the apo form of VCPO,
extracted from C. inaequalis followed by its reaction with
p-nitrophenylphosphate, at a resolution of 1.5 A.87 This is a
real reaction intermediate illustrating the inorganic phosphate
release of a dephosphorylation process. The trapped interme-
diate is the metal active site akin to a ‘metaphosphate anion’
covalently bonded to the nitrogen atom of His-496. The apical
water molecule located within the hydrogen-bonding distance
to the phosphorus atom is in a perfect position for a nucleo-
philic attack on the metaphosphate–histidine intermediate
which would generate inorganic phosphate.88
3.13.3.1.4 Comparing the haloperoxidasesOther than the native state of the enzymes (apoenzymes),69,89
the crystal structures of different VHPOs have also been deter-
mined with several small molecules including azidovanadate,68
peroxovanadate,85 tungstate,90 and inorganic phosphate87 in the
active site of the enzyme. Comparison of the crystal structures of
VBPOs and VCPOs reveals an unexpected homology that the
vanadate-binding residues largely overlap (Figure 4) despite the
fact that these enzymes are distinct from each other.15,91 How-
ever, the primary amino acid sequences are conserved to only
�20% across the various families of VHPOs.69 Moreover, there
are a few residues near the active site that differ between VCPOs
and VBPOs such as Arg-395 in VBPOs is a tryptophan in VCPO,
and His-480 in VBPOs is a phenylalanine in VCPOs, while His-
411 residue in VBPO (from A. nodosum) is substituted by Phe-
397 in VCPO (Figure 4). Messerschmidt et al.74 have reported
a tetrahedral vanadate group at the active site in a His-496A
VCPO mutant, representing that the covalent histidine coordi-
nation is a requirement for the modification of the vanadium
coordination with an elongated and weak bond to the axial oxo
group. This hypothesis agrees with the missing haloperoxidase
activity of the H496A VCPOmutant. His-418 from VBPO forms
a hydrogen bond (2.9 A) at the e2 nitrogen to the carboxyl
oxygen of Asp-278,while in VCPO the catalytic histidine residue,
His-404, is hydrogen bonded to the carbonyl oxygen atoms of
Trp-289 and Ala-290. This dissimilar way of acting of the
catalytically active histidine residue may be responsible for the
observed differences in halide substrate specificity92,93 and pH
dependencies83,94 of both haloperoxidases (VBPOs and VCPOs)
due to different pKa values of the catalytic histidine residues.
Despite all these differences, the conserved vanadium-binding
site demonstrates a common genetic origin for both types of
vanadium-dependent haloperoxidases, VBPOs and VCPOs.
From Raman and UV–vis spectroscopic investigation, Molinari
et al. have demonstrated that a peroxo–oxo-bound umbrella
structure is present in VHPO enzymes and metal–organic com-
pounds designed to mimic VHPOs.95
3.13.3.1.5 Substrate activity by haloperoxidasesHaloperoxidases catalyze peroxidative halogenation reactions
and the halide-assisted disproportionation of hydrogen perox-
ide. If there is a convenient nucleophile, the reaction will occur
with HOX to form a diversity of halogenated reaction products.
The catalytic properties of VHPOs have been extensively studied
showing that vanadium remains in the oxidation state of
5 throughout the catalytic cycle.74 Hence, the oxidation of
the bromide ion cannot involve reduction of the metal ion in
the first step. Figure 5(a) shows a mechanism proposed by
Messerschmidt et al.74 for both the VBPO- and VCPO-catalyzed
halide oxidation reactions. The active center binds peroxide
in a side-on fashion and appears to perform as a Lewis acid
in polarizing the bound-activated peroxide for further nucleo-
philic attack by an incoming halide. Lys-353, which is the only
amino acid interacting directly with the peroxo ligated moiety,
polarizes the peroxo bond, making it more susceptible toward
H
HH HH
H2O2
OH
OH
Cl OH
-OOH
O
OO
O
O
V
V
V
V
O
O
O
O
O
OO
O
O
N(His404)
N(His404)N(His404)
HOCI
N(His404)
N(His496)
N(His496)
N(His496)(a)
N(His496)
Cl-
Cl--2H2O
H+, H2O
Full mechanism
RX + H+
RH
H
H2O2
H2O
H2O2 + 2 OH-
H+
H+
essential
Assisted by H+
Site of substrate attackH(b)
O2 + X−
+ 2 H2OO
O
OO
O
O
OO
OO
OH-
X−
‘X+’ + L-V
L-V
L-V
L-V
Probably protonated
Figure 5 (a) Proposed reaction mechanism for the VHPO-catalyzed oxidation of chlorides. Reproduced from Ligtenbarg, A. G. J.; Hage, R.;Feringa, B. L. Coord. Chem. Rev. 2003, 237, 89, with permission. Copyright 2003 Elsevier. (b) Alternative reaction mechanism for the catalyzed oxidationof halides accounting for the observed Hþ-dependence. (from Zampella, G.; Fantucci, P.; Pecoraro, V. L.; De Gioia, L. J. Am. Chem. Soc. 2005,127, 953).
328 Vanadium Biochemistry
nucleophilic attack.96–98 Indeed, a mutagenesis experiment
supported this possibility for the K353Amutant.99 The hydrogen
bonding of the peroxo vanadium intermediate is important for
the properties of the different enzyme intermediates and further-
more calls for the involvement of charged residues required for
charge neutralization of this system. The Polenova group has
showed using solid-state 51V NMR spectroscopy that the vana-
dium cofactor in the resting state of VCPO contains one hydroxo
group in the axial and equatorial planes. The combination of
density functional theory (DFT) and solid-state NMRparameters
supports the interpretation that the cofactor is likely anionic
in the resting state of the enzyme and is involved in an extensive
H-bonding network.100
Several lines of evidence have been reported pointing to the
charge of the cofactor and the involvement of the proton in
the conversion of H2O2 to H2O using model compounds and
the enzyme. The Pecoraro group examined a number of simple
functional model systems containing the oxo-peroxovanadium
functionality.101 Of these, the complex [VO(O2)(Hheida)]�
(Scheme 2) where H3heida is (2-hydroxyethyl)iminodiacetic
acid, became the gold standard, and has been most exten-
sively studied mechanistically. Studies with this system and
others documented the role of the hydrophobicity of the envi-
ronment.102Theneed forprotonationof the reaction to takeplace
in model systems requires the mechanism in Figure 5(a)101,102
to be modified to that shown in Figure 5(b).96–98
OO
OO OHO O
N
O
V
–
Scheme 2 The oxoperoxovanadium(V) complex formed with theH3heida ligand.
Vanadium Biochemistry 329
Quantum mechanical studies first on the resting state of
the haloperoxidase probed the structure of the vanadium
center.96,103 The reaction with H2O2 as well as formation of
various other intermediates were also investigated.96 These
studies show that the formation of the side-on peroxide is
catalyzed by acids and bases.96,97 Computations on the
model system have continued to explore the reaction interme-
diates and transition states comparing the enzyme with the
oxoperoxovanadium(V) compound of H3heida. This leads to
the demonstration that the protonated model peroxide system
is competent to oxidize both bromide and iodide but not
chloride98 in contrast to VCPO that can oxidize chloride, bro-
mide, and iodide. The origin of this discrepancy is due to the
difference of their redox potentials and in part the increasing
basicity of the peroxide resulting from poorer orbital overlap in
the transition state with the halide favoring deprotonation of
the protonated peroxide.98 X-ray absorption near edge struc-
ture (XANES) spectroscopy has been obtained to support this
hypothesis by demonstrating that the peroxo–oxo intermedi-
ate does not contain a protonated oxo-group under catalytic
conditions.98
So far, a distinct halide binding to the vanadiumhas not been
found for any VHPOs. No crystallographic evidence is available
that includes a coordinated halide.104 Further, no kD’s have been
determined for halide binding to these enzymes. The halide
may not interact strongly with the enzyme until the peroxo inter-
mediate is formed suggesting that addition of halide to crystals in
the peroxo form results in enzyme turnover and cracking of the
crystals. When A. nodosum was treated with bromide in the ab-
sence of H2O2, it was proposed that Br is bound to the Ser-416
residue.105,106 However, Feiter et al. employing a combination of
experimental and modeling studies have demonstrated that the
native A. nodosum contains Br in the surface of Tyr-447 and Tyr-
398 residues.107 They proposed that these brominated Tyr resi-
dues are not likely to be reactive intermediates in the VBPOs
catalytic cycle since they are located at the surface of the protein.
The observed biochemical difference between VBPO and VCPO
in regard to their CPO activity10 is attributed to the second
histidine residue, His-411 in VBPO, which is in close contact
with the peroxovanadate center. Whether the substrate reacts
predominantly with free HOX or with some form of enzyme-
bound V–OX (X¼halide) intermediate is still uncertain.15,91
Some results dictate that these enzymes can catalyze reactions
with regioselectivity or enantioselectivity, demonstrating the in-
volvement of trapped Xþ equivalents15,108,109; whereas others
show no selectivity or mechanistic flexibility.15
Anderson et al. discovered that the VBPO isolated from the
algaCorallina officinalis catalyzes the oxidation of bicyclic sulfides
to the corresponding sulfoxides with 91% enantiomeric
excess.110 Later, Wever et al. reported generation of chiral sulfox-
ides with high enantiomeric excess employing a range of different
substrates, such as methyl phenyl sulfide, methyl p-tolyl sulfide,
1-methoxy-4 (methylthio)benzene, etc.111–113 The recombinant
VCPO from the fungus C. inaequalis catalyzes the oxidation of
2,20-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), a
typical heme peroxidase substrate.114 Wever et al. also proposed
the mechanistic pathway for the oxidation of sulfides by VBPOs
and VCPOs based on the ternary structure of the peroxo-bound
intermediates (Figure 6). Werncke et al. reported the synthesis of
a novel oxovanadium(V) complex. This complex in the presence
of added H2O2 undergoes a sequence of successive peroxide
formation, and intramolecular thioether oxidation events (sulf-
oxide and sulfone) and form a mixture of five products, which
were all identified unambiguously, partly through an indepen-
dent synthesis and characterization.115 The mechanism for the
formation of thioether and sulfide also involves a critical proton-
ation step of theperoxidemoiety as demonstrated experimentally
and theoretically.98
Wischang et al. reported the synthesis of immobilized en-
zyme of VBPO on magnetic micrometer-sized particles with a
half-life time of about 160 days which acts as a reusable catalyst
for bromide oxidation with H2O2.116 They have also noticed
that VBPOs in the presence of H2O2 and NaBr are effective for
electrophilic aromatic bromination of ester-, cyano-, and
carboxamide-substituted 1H-pyrroles.116 The VHPO extracted
from the brown alga L. saccharina is capable of catalyzing the
formation of a black precipitate, when reacted with L-3-(3,4-
dihydroxyphenyl)alanine (DOPA) in the presence of hydrogen
peroxide and iodide. The L-DOPA oxidation is a multistep
reaction with a crucial role played by the iodide in the
enzyme-catalyzed peroxidative production of dopachrome, a
well-known intermediate in the synthesis of melanin.117 The
interaction between phenolic substances (PS) and alginates
(ALG) was probed via size exclusion chromatography (SEC),
and optical tweezers microscopy has been proposed to be
catalyzed by VBPOs.118
Finally, VCPOs and its mutant P395D/L241V/T343A were
investigated by Renirie et al. for their antibacterial and antiviral
action at pH 8.0 and at a low H2O2 concentration and exhib-
ited a broad spectrum of antimicrobial activity.119
3.13.3.1.6 Phosphatase activity by haloperoxidasesWever and coworkers have demonstrated that the amino acid
residues of the active site of VHPOs are conserved within three
families of acid phosphatases.120 Furthermore, they have shown
that apo-CPO can also function as an acid phosphatase.120
Structural analogy between the two classes of enzymes is readily
illustrated from the crystal structure of the active site of rat
prostatic acid phosphatase (Figure 7) complexed with vanadate
which is bound in the same trigonal bipyramidal geometry as in
VCPO (Figure 2).85,121,122 His-496, which is axially coordinated
to the vanadium in apo-CPO, is a part of an extensive hydrogen-
bonding network in the protein.85 In rat prostatic acid phos-
phatase, the vanadate is also covalently bonded to a His-12
while Arg-11, Arg-15, Arg-79, and His-257 are within
hydrogen-bonding distance.120 VCPO from the fungus C. inae-
qualis exhibits both haloperoxidase and phosphatase activities
and is related to glucose-6 phosphatase.123
Arg-79
Arg-15
Arg-11
Asp-258
His-12
V O N C
His-257
Figure 7 Active site of rat prostatic acid phosphatase. Adapted fromPlass, W. Angew. chem. Int. Ed. Engl. 1999, 38, 909, with permission.Copyright 1999 Wiley-VCH.
O
OO
O
ON
N
V
His
OO
O
ON
N
V
His
SS .+
SR2
R2
R2S
OR2
R1
R1
R1
S
R2e-
δ+
δ-δ-
δ+
R1
R1
Figure 6 Schematic presentation of the critical sulfoxidation exhibited by VBPO (left) and recombinant VCPO (right). Reprinted from ten Brink, H. B.;Schoemaker, H. E.; Wever, R. Eur. J. Biochem. 2001, 268, 132, with permission. Copyright 2001 Elsevier.
330 Vanadium Biochemistry
Peroxidase activity exerted by the phosphatases has been
investigated by several researchers.120,124–126 Incorporation of
vanadate ion, in the presence of H2O2, into the active site of
phytase, which in vivo mediates the hydrolysis of phosphate
esters, resulted peroxidase activity.125 Whether the dual activity
of these enzymes observed in vitro extends the role of these
enzymes in vivo remains to be explored in future. However,
despite the striking similarity in the active site structures of
the VHPOs and the acid phophatase, the turnover numbers
for the phosphatase from Shigella flexneri and Salmonella
enterica ser. Typhimurium are low.126 Clearly the active sites of
acid phosphatases are not optimized for haloperoxidase
activity.126 Moreover, Lys-76 in glucose-6-phosphatase was
predicted to stabilize substrate by hydrogen bonds as Lys-353
in VCPO, but this residue appears to be in a membrane-bound
section of the protein.4 Given the variation in reaction
mechanism even among the VBPO and VCPO enzymes, diff-
erences between VHPOs and a few phosphatases are not
anticipated.4
3.13.3.2 Nitrogenases
3.13.3.2.1 General overviewThe vanadium(V) nitrogenase (VNase) was isolated and puri-
fied for the first time in 1986 by Hales and coworkers127,128 as
an alternative nitrogenase that is expressed under Mo-depleted
environments.19,129–133 VNases have been found in the free-
living soil bacteria of the genus Azotobacter chroococcum and
A. vinelandii. VNases that have the molybdenum sites are
replaced by vanadium and consequently have unique proper-
ties with distinctive differences in the mechanism of nitroge-
nase catalysis.127,128,134 The VNase is less understood than the
MoNase135; however, as recently described, a new form of
VNase has been isolated, and decreasing the heterogeneity of
these sample is assisting in characterizing the active site geom-
etry and the mechanism of this enzyme.136
3.13.3.2.2 Structural perception and amino acid sequenceIn analogy with the Mo analog (MoNase), the VNase consists
of an iron protein (encoded by vnfH) which is a homodimer of
MW 64 kDa and an iron–vanadium protein (encoded by
nifDGK) (Figure 8) of MW 240 kDa.135,137 The VNases isolated
from A. vinelandii and A. chroococcum have extensive DNA
sequence homology with MoNase. Recently, the isolation of a
homogeneous, His-tagged form of VFe protein from A. vinelan-
dii has a different a2b2g4-heterooctameric composition and is
catalytically distinct from the MoFe protein.136
VNases catalyze the conversion of N2 to NH3. Table 1 sum-
marizes the amino acid sequences for the three vnf-coded VFe
proteins in VNases. As in MoNase, the vnfH-encoded Fe pro-
tein component in VNase (Figure 8) contains two a subunits,
which are bridged by a [Fe4S4] cluster, ferredoxin, and also
includes a MgATP-binding site.137–140 The nifDGK encoded
V-Fe protein (Figure 8) has an a2b2d2 octameric structure that
contains two types of inorganic clusters, a P-cluster (Fe8S7) at
Vanadium Biochemistry 331
the interface of a and b subunits and a two iron–one vanadium
cofactor (FeVco), located in each a subunits.19 Spectroscopic
and size extrusion studies have revealed a close functional
homology by the P and FeMco clusters (M is either V or
Mo).141 The unique structure of the inorganic cluster
(P-cluster) has led researchers to believe that this cluster serves
as an effective mediator to transfer electrons to the catalytic
component, FeMco cofactor, in all three nitrogenases. The
FeMco clusters may adopt different oxidation states for the
catalytic reduction of a wide variety of substrates.130 Unfortu-
nately, till date there is no structural characterization for VNase
except for solution studies; however, the active centers present
in VFe proteins have been investigated by EPR, Mossbauer,
Fe protein
Fe4S4
MgA
TP
MgA
TP
e-
P-cluster
FeVco
VFe protein
β α
δ δ
Figure 8 Schematic representation of the components of VNase.Adapted from Hu, Y. L.; Ribbe, M. W. Acc. Chem. Res. 2010, 43, 475,with permission. Copyright 2010 American Chemical Society.
Table 1 Amino acid sequences flanking His-442 of the a subunitin VFe proteins
Source Sequence Ref.
A. vinelandii Tyr-Val-Asn-Gly-His-Gly-Tyr-His 138A. chroococcum Tyr-Val-Asn-Gly-His-Gly-Tyr-His 139An. variabilis Tyr-Val-Asn-Gly-His-Gly-Tyr-His 140
Ac2v(MgATP)2 + Aclv
Ac2v
Ac2v(MgADP)2
2MgADP
2MgATP
k+1
KDMgADP
KiMgATP
k–1
Ac2v(MgATP)2A
Figure 9 MgATP-induced electron transfer from Fe protein (Ac2V) to VFe pThorneley, R. N. F.; Bergstrom, N. H. J.; Eady, R. R.; Lowe, D. J. Biochem. J.
MCD, XANES, and EXAFS studies. The resonance at g¼5.5
(from EPR) suggests the spin state in the protein is 3/2 and
the available studies suggest that the oxidation state of vana-
dium lies between (II) and (IV).4,19,142,143 However, with the
report of a homogeneous, His-tagged form of VFe protein from
A. vinelandii differences is observed compared to the MoFe
protein suggesting that this form of the protein is slightly
different from the older forms described above.135,136
3.13.3.2.3 Enzyme catalysisMgATP-induced electron-transfer kinetics of VNase has long
been a benchmark for dinitrogen chemists and this process
was studied very systematically by Thorneley et al.144 for
VNase isolated from A. chroococcum by using stopped-flow
spectrophotometry at 23 �C and at pH 7.2 (schematically
represented in Figure 9). The first two steps of the catalytic
cycle of Nase turnover, that is, the binding of MgATP to the Fe
protein and the electron transfer from the Fe-protein to the VFe
protein, result in the formation of a complex similar to those
formed by MoNase isolated from Klebsiella pneumoniae.145 At
high MgATP concentration, first-order kinetics is observed with
a rate constant of kobs¼46 s�1. MgATP binds at the interface
between VFe and Fe proteins with the apparent binding con-
stant kD¼230�10 mM. The dependence on MgATP concentra-
tion and its competitive inhibition by MgADP were very
similar to those of MoNase isolated from K. pneumoniae.145
Because of these and other similarities between the VNase with
MoNase, it is not surprising that VNase will catalytically resem-
ble MoNase and will be a proficient catalyst for a range of
substrate turnovers.
3.13.3.2.4 Dinitrogen reductionThe biological function of VNase is the production of ammo-
nia from dinitrogen, which sequesters dinitrogen gas in a
biologically accessible form. Like MoNases, the alternative ni-
trogenase, VNase, uses MgATP.19 Both the electrons and the
ATP in this system are provided through photosynthesis. The
absence of dioxygen and a low-potential reductant, usually
dithionite (S2O42�), are the other two requirements for this
enzyme complex for enzyme activity. Although in general,
Nase activity toward N2 is depicted by eqn [2], for VNase the
distribution of e�, proton, and MgATP and the overall compo-
sition of the products of the reduction reaction is somewhat
modified and is represented by eqn [3].19 More H2 is generated
for each NH3 produced and, therefore, more ATP is required
for N2 reduction by the VNase as compared to the MoNase
k+2clv Ac2v (MgADP + Pi)2 Aclvred.ox.
rotein (Aclv) and inhibition of this reaction by MgADP. Adapted from1989, 257, 789, with permission. Copyright 1989 Portland Press Limited.
332 Vanadium Biochemistry
(eqn [2]).146 The rate-determining step for this reduction reac-
tion is the dissociation of the MgADP–Fe protein bond in the
transition state.19 Equations [2] and [3] demonstrate that
Nases also hold an inherent hydrogenase (Hase) activity that
results in a mandatory production of hydrogen gas.
N � Nþ 12Hþ þ 40MgATPþ 12e�
! 40MgADPþ 40Piþ 3H2 þ 2NH3 [3]
VNase, unlike MoNase, has the propensity to form low but
significant amount of hydrazine (N2H4) following eqn [4] (up
to 0.5% of the reduction equivalent resulting in the dinitrogen
reduction) during its catalytic dinitrogen fixation.147 Figure 10
summarizes the catalytic conversion of N2 to NH3 along with
the minor generation of N2H4 as a side product. When the
VFe protein was combined with purified Fe protein of either
VNase or MoNase, N2H4 was detected while combination of
MoFe protein with two Fe proteins does not form N2H4.148
N � Nþ 4Hþ þ 4e� ! N2H4 [4]
3.13.3.2.5 Carbon monoxide reductionVNase reduces the substrate N2 but can also reduce carbon
monoxide (CO) to hydrocarbons with the concomitant reduc-
tion of the proton to H2 gas149 as shown in eqn [5]. The
formation of hydrocarbons by VNase was inhibited by the
addition of increasing amounts of H2, which implies that H2
is an unlikely hydrogen source for this reaction. Considering
the isoelectronic properties of N2 and CO and the similarities
between the reactions shown in eqns [4] and [5]
some similarities for both N2 and CO reduction reactions
will take place with both substrates. More distinct differences
have recently been observed with varying enzyme composi-
tion, and it is possible that some of the early studies may
need to be revisited with this new purer form of the
VNase.135,136 The intramolecular hydrogenation mechanism
earlier proposed for N2 reduction (including H-atom tunnel-
ing) can also effect reduction of CO. The possible steps for the
overall reaction are: (1) CO binding, (2) CO to HCO conver-
sion, early hydrogenation, (3) persisting hydrogenations of
CO at both C and O to form HCOH and H2COH, (4) O
eliminations of H2O, and (5) the formation of a C–C bond.
Intermediate organic fragments can migrate around the FeVCO
N2
NH3
M
M-NH2
N2H4
NH3
M=N-NH2M-NH-NH2
M=NH
M-N N M-N NH
(A)(B)
M=N-NH3-
Figure 10 Cycle for the stepwise protonation of coordinated N2 onVNase to give NH3 or N2H4. Reproduced from Dilworth, M. J.; Eady, R. R.Biochem. J. 1991, 277, 465, with permission. Copyright 1991 PortlandPress Limited.
active site, and hydrogen bonding between COH functions and
S or SH components of FeVCO protein can occur
and contribute to the stabilization and orientation of the
intermediates.150 The ability of VNase to catalyze both CO
and N2 reductions shows that similar reactions can occur in
the carbon cycle as it takes place for nitrogen cycles. Indeed, in
the reactions using CO as a substrate the difference between
the MoFe and VFe enzymes is underlined,136,151 particularly
with regard to the higher product alkanes that have been
reported recently.151
COþHþ þ ATP ! C2H6 þ C2H4 þ C3H8 þ C3H6
þ ADPþH2 [5]
3.13.3.3 Vanabins
Several vanadium-containing proteins from the cytoplasm
of the vanadium-containing blood cells referred to as vana-
docytes from A. sydneiensis samea have been identified by
Michibata et al.22–26 When first discovered, these proteins
were known as vanadium-associated proteins (VAPs).25 Of
these proteins, vanabin1 and vanabin2 with apparent molec-
ular weights 12.5 and 15 kDa, respectively, are rich in lysine
and cysteine residues. Michibata et al. have determined the
affinities of vanabin1 and vanabin2 for vanadium(IV). They
have shown that the two vanabins bind multiples of 10 and 20
vanadium atoms per protein with dissociation constants of
2.1�10�5 and 2.3�10�5 M, respectively, indicating differ-
ences in amino acid sequences in these proteins.25,152
Vanabin1 and vanabin2, which are respectively composed
of 87 and 91 amino acids, each contain 18 cysteines and 12
and 14 lysines, respectively.23 Only Cu(II) reduces vanadium
binding while other metals, for example, Mg(II) or Mo, do not.
Two other vanabin-like-proteins, known as vanabin3 and
vanabin4, have primary structures which closely resemble
those of vanabin1 and vanabin2.152 Recently, Michibata et al.
have isolated and analyzed the fifth type of vanadium-binding
protein known as vanabinP (vanabin in plasma) available in
blood plasma of the ascidian A. sydneiensis samea.152 Based on
EPR spectroscopic titrations and ESEEM studies (Figure 11), it
has been shown that vanabin2 can bind up to 23.9 vanadium
ions per protein where the vanadium ions are in mononuclear
state and coordinated to amine nitrogen.153 Regardless of the
high number of cysteines in these proteins, no evidence was
found for thiolate coordination to the vanadium. Michibata
suggested that the roles of these vanabin proteins are to trans-
port the vanadium to the vacuole.153
3.13.4 Organisms Accumulating Vanadium
3.13.4.1 Tunicates
3.13.4.1.1 General overviewTunicates, also referred to as sea squirts or ascidians, so named
because they release jets of water through their siphons when
disturbed are a class of common marine invertebrate organ-
isms that selectively accumulate metal ions such as V, Fe, Mo,
and Nb from seawater.27,154 Tunicates get their name from
their tough, often translucent, tunic-like body. It was Martin
Henze154 who first discovered that the Mediterranean ascidian
260 300 340
B (mT)
380
1:20
3.9
00
3τ (μs)2.8 7.1
13.7= ν(1H)
[Vanabin] : [V]
420
0
0Four
ier
amp
litud
e (A
.U.)
5 10 15Frequency (MHz)
Figure 11 EPR (left) and ESEEM (right) and its time domain data (right, inset) spectra of VO2þ and vanabin2. Reproduced from Fukui, K. I.; Ueki, T.;Ohya, H.; Michibata, H. J. Am. Chem. Soc. 2003, 125, 6352, with permission. Copyright 2003 American Chemical Society.
OHOH
OH
OHOH
OH
O
NHHO
NH
HO
HO
HO
H2N
Figure 12 Structure of tunichrome. Redrawn from Bruening, R. C.;Oltz, E. M.; Furukawa, J.; Nakanishi, K.; Kustin, K. J. Am. Chem. Soc.1985, 107, 5298, with permission. Copyright 1985 American ChemicalSociety.
Vanadium Biochemistry 333
Phallusia mammillata, phylogenically belonging to the
Chordata, accumulated high levels of vanadium in its blood
cells. The black tunicate, Ascidia nigra, sequesters vanadium
in its various cells as pentavalent monomeric vanadate and
concentrates it by �106-fold after reduction of the vanadium.27
It was early on suggested that low-molecular- weight pigments
known as tunichromes (Figure 12) serve as complexing agents
for the accumulation and storage of the intracellular
vanadium.27,155,156 The tunichromes constitute a series of com-
pounds isolated from the blood cells of ascidians that form the
major class of the subphylum Urochordata (Tunicata).6 The
distribution of vanadium and tunichrome among different cell
types has been studied by electron microscopy,157–159 cell
sorting,160,161 and by 2,2-bipyridine staining for vanadium
(III).159 In general, the signet ring and compartment cells contain
the bulk of the vanadiumwhile themorula cells are the source of
the tunichromes.160 Therefore, the possibility that the tuni-
chrome is bound to the vanadium and stored as chelates in the
tunicates is no longer supported by experimental results.
Ascidians provide the oldest known example of vanadium
sequestration in nature, and despite one century of research
since Henze’s discovery, a function for the metal remains
elusive. Considerable efforts have been made162 to understand
in what form, and why, vanadium is stored in these sessile
marine organisms. Researchers know that the sequestered
vanadium(V) is actually stored in its reduced forms either
as vanadium(IV) or as vanadium(III) at physiological pH
(�7.2), possibly in the hexaaqua form or as some other
complex species in specialized blood cells referred to as
vanadocytes.22,27,163–166 The vanadium concentration in the
vanadocytes is 0.15 M; however, in some vanadium-containing
vacuoles in the vanadocytes, the vanadophores, it can reach up
to 1 M.6 These organisms are the only organisms in which the
formation and existence of V(III) in biological systems have
been reported. Since it is not trivial to form vanadium(III)
under physiological conditions, even under reducing condi-
tions, the presence of a strong reductant that also serves as a
complexing agent would maintain vanadium in such a low
oxidation state.27 The generally accepted mechanism for this
sequestration process involves a reductive chelation reaction.27
For this, vanadocytes use a yellow green and fluorescent organic
chromogen named tunichrome (Figure 12), a powerful physi-
ological reducing agent which reduces V(V) to V(IV) or V(III) in
vitro and presumany facilitate the reduction before the vana-
dium reaches its final location in the vanadocytes.155,156
3.13.4.1.2 Oxidation state of vanadium in tunicatesVanadium is a versatile element that can exist in oxidation
states ranging from þ5 to �3 but þ5, þ4, and þ3 are the
oxidation states that exist at physiological pH.36,167,168 The
first suggestion by Henze154 that the vanadium existed in þ5
oxidation state in these organisms was rejected. Studies using
noninvasive physical methods, including spectroscopic (e.g.,
ESR, XAS, and NMR)169–173 and magnetic (SQUID)166,174 of
isolated extracts166,174 and whole cells,169–173 indicated that
the vanadium ions in ascidian blood cells were predominantly
in the þ3 and þ4 oxidation states.
V(III) is usually unstable toward air and moisture based on
its standard reduction potential value of 0.337 V (vs. NHE) in
strongly acidic solutions and are easily hydrolyzed to V(OH)2þ
above pH 2.5.27 V(III) species are generally not stable in neu-
tral and alkaline solutions and are maintained in aqueous
solution only in an acidic pH range under reducing conditions
or in the presence of strong complexing agents. Tunichromes,
the bright yellow blood pigments from A. nigra and other
various tunicates, can complex vanadium(III) and readily
maintain the vanadium in the low oxidation state at neutral
pH.175,176 However, considering that the tunachrome and va-
nadium are found in different cells,157–159 complexation may
facilitate reduction of the vanadium(III) but does not serve to
store the vanadium. Alternatively, vanadium ions are stable
under acidic conditions within the blood cells of ascidians.
The possibility whether vanadium existed in two oxidation
334 Vanadium Biochemistry
states (þ3 and þ4) in one type of blood cell, or is each state
formed in a different cell type was investigated by Michibata
et al.177,178 when they conducted noninvasive EPR measure-
ments of blood cells of A. gemmata. Their study showed that
the oxidation state of vanadium in these vanadocytes is pre-
dominantly þ3, with some vanadium being in the þ4 oxida-
tion state. The ratio of V(III) to V(IV) was 97.6:2.4.177
3.13.4.1.3 TunichromesTunichromes were discovered and characterized in the quest
for compounds that are involved in vanadium accumulation
and reduction in ascidian blood cells.156,160 Evidence would
also be formed via blood cytolysis.156,160 In the crude state,
tunichromes are extremely labile and consist of a complex
mixture of closely related compounds, which is why the com-
pounds eluded isolation attempts.22–27 Tunichromes contain
TOPA (3,4,5-trihydroxyphenylalanine) residues, and reducing
amino acids with strong metal chelating prospective through
their catechol and pyrogallol moieties, respectively.27,155,156
The first reported tunichrome, An-1, was isolated from the
phlebobranch ascidian A. nigra.155 It contains a modified tripe-
ptide of three TOPA units (Figure 12) while the structures of
An-2 and An-3 were determined, differing only in the degree of
hydroxylation.156 Once isolated in the pure form, the tuni-
chromes become more stable. Three more tunichromes desig-
nated as Pm-1, Pm-2, and Pm-3 were identified from the blood
cells of P. mammillata.27 The presence of the pyrogallol moiety
in tunichromes provides the reduction potential in these com-
pounds making it kinetically competent to reduce V(V) to
V(IV) or V(III). For some time it was believed to resolve the
long-standing controversy regarding the mechanism of V(V) to
V(II1) reduction in ascidians. From the structures of the tuni-
chromes it is clear that their biosynthesis occurs through cou-
pling of three amino acids, enzymatic dehydrogenation, and
sequential hydroxylation. The major observations supporting
the existence of tunichromes in intact blood cells is the yellow
color of tunichromes, and this is also the case for the morula
35 nM V(V)in seawater
Metal transporter
V
V
V
NAD
V-ATPase
Branchial sac
Vanabin
Vanadocyte
Figure 13 Schematic presentation of vanadium accumulation and reductionUeki, T. Coord. Chem. Rev. 2003, 237, 41, with permission. Copyright 2003 E
cells, which can be observed by light and fluorescence
microscopy.28 Recently, the location of the tunichromes and
vanadium has been found to deviate, which suggests that
although tunichromes may be involved in bioprocessing of
the vanadium, tunichromes do not serve to store the vanadium
by complexation.22
3.13.4.1.4 Vanadium accumulation and reductionin tunicatesAscidians accumulate vanadium to levels more than 10million
times higher than that in seawater and have attracted the
curiosity of researchers for decades. Two suggestions have re-
ceived most consideration: vanadium(III) is stabilized in a
strongly acidic intracellular milieu,163,169,179–181 or vanadium
(III) is stabilized by chelation to an endogenous ligand.182,183
These suggestions have been evaluated considering cellular
energy requirements, suitable ligands, and the local pH.
The million-fold concentration of vanadium from seawater
constitutes a sizable metabolic energy allocation. The uptake
likely follows one of the two routes: (1) distribution of vana-
dium(V) between the plasma and blood cells governed by
direct uptake from the plasma into the blood cells, or alterna-
tively, (2) via vanadium influx into a tissue and a slow uptake
into the blood cells.29 The second pathway results in either loss
of vanadium from remote sites into the plasma along with
incorporation into the blood cells or alternatively production
and development of blood cells. Neutron activation analysis
by Michibata et al. showed that the vanadium accumulation
begins abruptly 2 weeks after fertilization, and continues so
that after 2 months, the amount of vanadium in larvae is
600 000 times higher than that in the unfertilized egg.184
The accumulated vanadium is mainly stored in vacuoles.
The vanadium-binding proteins, vanabins, facilitate the trans-
port and accumulation of the vanadium into these vacuoles,
as shown in Figure 13. 51V NMR shows that vanadium(V)
persists in the blood plasma before the accumulation takes
place. Because vanabins bind vanadium(IV) stronger than
350 mM V(III)
Metal transporter
III
PH
H+
IV
IV
H+
Cytoplasm
Vacuole
500 mM SO42-
SO42-
SO42-
pH 1.9
in ascidians. Adapted from Michibata, H.; Yamaguchi, N.; Uyama, T.;lsevier.
Vanadium Biochemistry 335
vanadium(V), it is likely that the reduction of the vanadium
happens before the vanabins bind the vanadium. Hence the
process of accumulation of the vanadium into the vacuoles
facilitates the reduction of V(V) to V(IV) and V(III). It has
also been suggested that this reduction involves NADPH.4,22
3.13.4.2 Amavadine
3.13.4.2.1 General overviewAmavadine is the only known vanadium-containing natural
product and consist of a 1:2 complex of a vanadium(IV) with
two ligands l,l-N-hydroxyimino-a,a0-dipropionic acid
(H3hidpa) (1 and 2, Scheme 3).185–191 It is isolated from a
mushroom of the genus A. muscaria and it does not resemble
the vanadium in the tunicates (also referred to as hemovana-
din) with respect to valence state or ligand.192 Identification of
the ligand (H3hidpa) associated with amavadine was done
using a combination of spectroscopy and synthesis. In 1986,
Bayer et al. reported a non stereoselective synthesis of the
ligand (H3hidpa), including a nonroutine separation proce-
dure of the ligand diastereomers, followed by insertion of the
vanadium to generate amavadine.193 The presence of the
hydroxylamido and carboxylate groups makes this microbial
ligand, H3hidpa, a very efficient chelating agent for a range of
metal ions of which vanadium ion has the highest affinity
(log K2¼23).189 Other metal complexes with H3hidpa (e.g.,
Mo, U, Nb, Ta, Ti, Zr, etc.) show chemical and structural
properties similar to amavadine.194–197 This natural product
has a unique structural feature, chemical environment, and
properties, and has generated interest to further examine this
class of compounds, and their chemistry.
3.13.4.2.2 Structure and reactivityThe fly agaric toadstool, A. muscaria, is remarkably rich in
vanadium with up to 400 mg kg�1 (dry weight) of
OO
OHOH
OH
N
N
O
OH
O
H
O
O
OO
N
N
V
O
V
OO
O
N
NO
O
O
HO
1 2
4
Scheme 3 The structures for the ligand (1), the vanadium(IV) complex (2),t(IV) model compound (5) and the ligand diacetyl hydroxylamine (6).
vanadium,198 mainly in the bulb of the mushroom. In 1972,
Bayer and Kneifel185 first isolated a blue, and very stable
vanadium-containing compound from A. muscaria and
named it amavadine (structure 2, Scheme 3).185 Since then,
several reports describe the structural investigations of the
natural product amavadine,35,187,193,199 its role in
biology,35,187,193,199–202 investigations into the properties of
the ligand H3hidpa,195–197 and identification of new species
and its complexes with other metal ions.195–197,203–205
The initially proposed molecular composition of amava-
dine was [VO(H2hidpa)2] (3, Scheme 3) where an oxovana-
dium(IV) center contains two molecules of N-hydroxy-2,20-iminodipropionic acid (H3hidpa) as a bidentate (O,N) donor
ligand, in monoprotonated form with a square pyramidal
coordination geometry surrounding the metal active center.185
In 1986, Bayer et al. reported the total synthesis of amavadine
leading to the structural revision and characterization of the
eight-coordinate, non-oxo complex currently known as ama-
vadine (2, Scheme 3).35,193 Comparing formation constants
between iminodipropionic acid (4, Scheme 3) and H3hidpa
with vanadium(IV) demonstrate the necessity of expanding the
coordination sphere and involving the N–OH group in coor-
dination to the vanadium.4,200 An analog of amavadine (5,
Scheme 3) based on the ligand N-hydroxyiminodiacetate
(H3hida) (6, Scheme 3) did not contain any IR band at
980 cm�1. This clue led to the hypothesis that no V¼O moiety
was present in the natural product amavadine.4 The bond
lengths for the V¼O bond lie typically between 1.57–
1.67 A.54,84 The lack of a short V¼O bond in the EXAFS spec-
trum of amavadine indicated the absence of an oxo group at
the vanadium center.193
The non-oxo V4þ containing natural product has a novel
octacoordinated geometry with the highly distorted cubic
geometry containing two hidpa3� ligands, each bonded via
a Z2-N,O group, and two unidentate carboxylate donors
N
N
N
V
O
OH
OH
HO
HO
O
O
OH HO
O
O
O
O
OO
O
O
O
O
2-
O
O
OO
O
O
H2-
3
5 6
he original proposed structure (3), diisopropanyl amine (4), the vanadium
336 Vanadium Biochemistry
(1, Scheme 3).187 Prior to this report, Carrondo et al. decribed
the crystal structure for the amavadine analog [V(IV)(hida)2] in
which the alanine amino acid is replaced by a glycine.199
Garner et al.206 reported the crystal structure of amavadine
(Figure 14) isolated from A. muscaria on samples of natural
amavadine crystallized as phosphoric acid derivative or as its
Ca2þ salt. We now recognize that amavadine contains five
chiral centers both in the neutral and in the anionic forms:
four chiral carbons all having ‘S’ configuration associated with
the amino acid ligand and the fifth chiral center at the vana-
dium generated by the chelation of the multidentate ligands
about the vanadium. The racemic form contained equal
amounts of the Δ and the L helical forms of amavadine.187
Upon oxidation, the coordination geometry of the vanadium
center in amavadin and its analog does not change (Figure 15).
The oxidized amavadin complex and its analog thus offer a
unique opportunity to study the eight-coordinated vanadium
geometry as well as fundamental reactivity of the com-
pound.207–209 The x-ray structure of meso-amavadin revealed
O(8
O(
O(5)
C(6
C(5)
O(4)
O(14)
O(15) O(9)-
O(11)
O(13)bO(13)aO(12)
Ca(1)
C
Figure 14 Crystal structure of [Ca(H2O)5][Δ-V((S,S)-hidpa)2]2H2O. ReprodErtok, S. N.; Helliwell, M.; Garner, C. D. Angew. Chem. Int. Ed. 1999, 38, 795
Figure 15 Molecular structures of [PPh4][V(V)(hidpa)2]�H2O (left) and [PPh4atoms, white; carbon atoms, gray; nitrogen atoms, blue; oxygen atoms, red;Baruah, B.; Choudhary, M. A.; Crans, D. C.; Polenova, T. Dalton Trans. 2009,
that the negatively charged anionic species is joined into infi-
nite hydrogen-bonded chains, counterbalanced by cationic
hydronium species.210
The biological function of amavadine is still not known.
Amavadine is a weaker inhibitor for the sarcoplasmic reticu-
lum, Ca-ATPase,211 and a weaker effector of glucose uptake212
than compared to vanadium compounds that readily lose their
ligand.213 In addition, it was not found to show any anti-
diabetic properties and failed to lower elevated blood–glucose
levels in STZ-induced diabetic rats. Studies have shown that
amavadine can act in peroxidative halogenation, hydroxyl-
ation, and oxygenation of alkyl and aromatic substrates in
the presence of H2O2.4,214–216 Amavadine catalyzes the electro-
catalytic oxidation of thiols217 such as cysteine, glutathione,
mercaptoethanol, and other thiols in acidic solution.202 Sur-
prisingly, little work has been done including a stereochemical
analysis of amavadine during its catalytic action. Amavadine’s
hydrolytic stability is accompanied by its reversible one-
electron transfer reactions that has been linked to functions
C(9)
C(8)
N(2)
C(10)
C(12)
C(2)
C(3)
C(11)
O(9)
O(10)
O(1)
)
O(7)
6)
V(1)
O(3))C(1)
O(2)C(4)
N(1)
(7)
uced from Berry, R. E.; Armstrong, E. M.; Beddoes, R. L.; Collison, D.;, with permission. Copyright 1999 Wiley-VCH.
][V(V)(hida)2]�CH2Cl2 (right). Hydrogen atoms are color coded: hydrogenand vanadium atoms, green. Adapted from Ooms, K. J.; Bolte, S. E.;3262. Copyright 2009 Royal Society of Chemistry, with permission.
Vanadium Biochemistry 337
such as iron–sulfur proteins, cytochromes, and blue copper pro-
teins known to retain their structure during a one-electron redox
change.35,186,187 Both amavadine and its analog, [V(IV)(hida)2],
undergo a reversible one-electron redox process that is very sen-
sitive to solvent variation.201,209 The solvent sensitivity is attrib-
uted to the solvent interactions with the carboxylate groups of the
complex. The electron transfer reaction of amavadine and its self-
exchange rate constants have been determined.208,209
Information about the electronic properties of the vana-
dium center is important for understanding amavadine’s
chemical properties and its function. Oxidation using different
metrical parameters show smaller change indicating outer-
sphere electron transfer reaction in the V(IV)–V(V) redox cou-
ple of amavadine.217 DFT computations and quantum theory
of atoms inmolecules (QTAIM) analysis of the electron density
differentiate the stereoelectronic features of the V(IV) (inactive)
and V(V) (active) states of amavadine. DFT calculations di-
vulge that protonation of V(V) amavadine at a carboxylate
oxygen is not involved in the vanadium coordination, instead
favoring methyl mercaptoacetate (MMA) binding into the first-
coordination sphere of vanadium, by substitution of the ama-
vadine carboxylate oxygen. The kinetic and thermodynamic
feasibility of the V(V)-MMA intermediates formation is consis-
tent with the biological role as a redox mediator, which is
supported by electrochemical data.217
Reports have also appeared on the efficacy of amavadine in
converting methane into acetic acid in the presence of a perox-
odisulfate salt and trifluoroacetic acid (TFA).215,218 The catalyst
can remain active upon multiple recycling of its solution; how-
ever, the yields for this reaction are very low. Carboxylation
proceeds through free radical mechanisms. The one-pot carbox-
ylation of ethane to propionic and acetic acids with the former as
the main product has recently been reported from the laborato-
ries of Pombeiro and coworkers.216 Two mechanistic pathways
have been proposed for the formation of acetic acid, the leading
one via oxidation of ethane with conservation of the C–C bond,
and the other through breaking of this bond and carbonylation
of the methyl group by CO. The C–C bond is maintained in the
formation of propionic acid upon carbonylation of ethane. The
reactions proceed via both C- and O-centered radical formation.
The oxidized amavadin and its analog offer a unique
opportunity to study the electronic properties of an eight-
coordinate vanadium geometry by comparing the effect such
coordination has on the electric field gradient (EFG) and chem-
ical shift anisotropy (CSA) on the solid-state 51V NMR spectra.198
Crans and Polenova have reported large downfield chemical shift
of the 51V resonance and they attribute this effect to the unusual
coordination geometry. Buhl et al. have reported DFT calculation
results for the oxidized form of amavadine to account for its
observed 51V NMR chemical shift.219 DFT methods have also
been employed to calculate the electronic g tensors and hyperfine
coupling tensors for amavadine.220 We attribute the continued
interest in amavadine to the unique structural and electronic
properties of this complex.
3.13.4.3 Fan Worm
Pseudopotamilla occelata, fan worm of the polychaeta class
reported in 1993,221 was found to contain high levels of vana-
dium. The vanadium concentration is the highest in the
bipinnate radiole.222 Most of the vanadium is believed to be
in oxidation state (III) and a high level of sulfate is found in the
vanadium-containing cells.223,224 The role of vanadium in
these animals is to regulate the oxidation–reduction reactions
at the surface of the radiole, in the absorption of O2, and in
detoxification mechanisms. The vanadium-storage environ-
ment and form appear to be the same in this fan worm and
in ascidians.223,224
3.13.5 Insulin Enhancing Effect of VanadiumCompounds
In the sections prior to this, we have described in detail each
enzyme for which vanadium is a cofactor. These sections con-
cerned studies of systems in which the role of the vanadium
was determined by how it interacts with a protein. However,
vanadium is known to exert effects other than those that can be
traced back to an enzyme. This is undoubtedly due to vana-
dium’s ability to act as a phosphate analog when in oxidation
stateþ5, and as a divalent cation when in oxidiation stateþ4.4
Indeed, vanadium compounds have been reported to have
anti-diabetic, anti-cancer, and anti-cardiovasular effects.4 Al-
though description of these effects are less straightforward,
because there are several targets and the action of the com-
pounds is less defined, undoubtedly the mode of action of
these compounds will at some point involve interactions
with proteins and metabolites that can be understood and
used for further development. In this section, we describe one
such example, namely when vanadium compounds or salt
exhibit insulin-enhancing effects.4,47,225
The early discoveries by Shechter in cell studies226–229 fol-
lowed by the groups lead by Sakurai230–234 and McNeill235–243
demonstrated that vanadium found in simple salts had a ben-
eficial effect in animal systems. These studies launched an
effort to not only investigate how vanadium exerted its
insulin-enhancing action, but also the potential development
of this system into a drug. The latter studies were fueled by
the efforts of the Posner group244–253 which demonstrated
that vanadium as a peroxovanadium derivative was tenfold
more active than the simple salt, and as such had potential
as a drug. These studies formed the basis on which many
subsequent studies were based in our group and many
others,4,47,212,225,254–259 and have resulted in several studies
with both salts and a coordination complex in human
beings.242,243,260–264 Most well-known is the development of
a vanadium-containing coordination compound, bismaltolato
oxovanadium(IV), BMOV, subjected to phase I and II clinical
trials.237,242,243,265–268 Unfortunately, this endeavor has re-
cently been abandoned mainly because this compound will
no longer be protected by patent in 2015. As a result, this area
now needs new compounds with improved efficacy.242,243
During the early studies vanadium was believed to be able
to replace insulin; however, more recent reports have demon-
strated that the vanadium acts by enhancing the effect of
insulin, and thus less effective in systems in which no insulin
is present. For several decades, the focus was on investigation of
vanadium(IV) coordination complexes.230,231,233,235–243,269–275
However, more recent studies have demonstrated that several
vanadium complexes in oxidation states (V) and (III) also can be
338 Vanadium Biochemistry
effective as insulin-enhancing drugs.240,258,276 Regardless of the
oxidation state, the active vanadium compounds are potent in-
hibitors for protein tyrosine phosphatases, and since most phos-
phatases are inhibited by vanadium compounds, the selectivity
exhibited are based on thedegree of inhibition. That is, inhibition
of the protein tyrosine phosphatase, 1B (PTP1B), is very potent,
whereas the inhibition of other phosphatases such as serine
and threonine phosphatases is much less.246,259,277–281 Studies
have demonstrated that these studies are nontrivial because
often the vanadium compounds are not compatible with the
assay conditions used for such studies and complicating
the importance of these studies, and the results obtained will
not show a pattern.278,279
Recent studies in this area include exploring the distribu-
tion of vanadium compounds. Although vanadium first binds
to transferrin, some binding to other proteins in the blood
stream and formation of ternary complexes have been ob-
served under a range of conditions.282–289 These studies com-
bined with biochemical investigations into the cellular
responses290–292 are suggestive of a mechanism involving
some of the proteins associated with the signaling in the
cell293 which may involve action at the membranes.47,294–295
Regardless of the mode of action of these compounds, it ap-
pears that the ligand dissociated from the metal ion, and as a
result small differences between complexes efficacy has been
reported. Undoubtedly, if the mechanism for the beneficial
effects of these vanadium compounds can be elucidated,
there is a potential of using such information to develop new
and effective drugs against diabetes.
3.13.6 Conclusion
Vanadium is abundant in the biosphere. Nature has chosen vana-
diumas cofactor, for a range of enzymes that contain vanadium in
oxidation states (III) through (V) in their active sites, highlighting
the different roles for vanadium in biology. As a result a number
of reviews exist in the literature on different aspects of functional
and/or structural description of vanadium-containing biomole-
cules. This chapter focuses on the protein-based aspects of bioi-
norganic vanadium chemistry describing the coordination
chemistry of different classes of proteins that contain vanadium.
Markeddiversity inbiochemical activityof vanadium is associated
with its oxidation state. In order to illustrate how the chemistry of
vanadium contributes to life process in the biosphere, vanadium
interactions in the biological systems are detailed.
Beginning from the discovery of the first vanadium-
containing enzymes, VHPOs, in 1984 to the current under-
standing of the details in the five-coordinate vanadium com-
plex with the side-on peroxo group has uncovered the the
importance of protonation for the catalytic process. The com-
bination of structural characterization withmechanistic studies
together provides a more complete description of the systems
allowing a comparison between the VBPO and VCPO, and
furthermore allows a comparison of relationship between per-
oxidases and phosphatases. Two classes of enzymes that once
were so distinct have now been demonstrated to have signifi-
cant sequence, structural, and functional analogy.
Microorganisms use vanadium as an essential trace element
for their enzymatic processes such as two-electron oxidation of
halide to HOX and nitrogen fixation via biological conversion
of atmospheric dinitrogen to bioavailable ammonia. The
vanadium-containing nitrogenase, VNase, is an anaerobic en-
zyme that forms under condition when molybdenum is defi-
cient. The vanadium will then replace the position of the Mo in
the cofactor and as such the protein is competent to do many
of the reactions the MoFe enzyme carries out. There have been
some model studies in this area generally involving the low
oxidation states of vanadium.
Metal accumulation by living organisms is an important
aspect of bioinorganic chemistry, but the mechanisms for
these processes remain underexplored in vanadium biochem-
istry. Despite the fascination with tunicates and their function
of accumulation of vanadium from seawater, the mechanism
for concentration is poorly understood, perhaps in part be-
cause information on oxidation state(s), location of the vana-
dium, and the molecular biology was the initial focus of these
studies. In the coming years the role and action of the vanabins
will be further elucidated and the transport of vanadium from
the seawater to the vacuoles will be further elucidated. Further-
more, information on how the concentration of the metal ion
is directed so that it can carry out one or more of its biochem-
ical functions will be characterized.
The presence of vanadium in several accumulators such as
the mushroom A. muscaria, marine invertebrate tunicates, and
the fan worn P. occelata has also drawn significant interest in
vanadium biochemistry. Much less is known about these sys-
tems, and the majority of the work carried out thus far focuses
on identification of what form the vanadium is in. In the case of
the mushroom, the vanadium is placed in a dodecahedral coor-
dination environment with two tetra-coordinated ligands and is
a non-oxo complex. This compound has reversible redox chem-
istry in aqueous solution, and as such serves as an ideal tool to
investigate fundamental aspects of redox chemistry. The natural
product is believed to be involved as redox mediator.
The insulin-enhancing mechanism of vanadium com-
pounds is a complex topic, which continues to evolve. The
compounds that have been front-runners for the past decade
have not only shown promise in animal studies but some of
them have also been investigated in human studies. Indeed,
the ability of vanadium compounds to lower elevated blood–
glucose levels but not go significantly below normal glucose
levels is a very desirable effect of an anti-diabetic drug. Increas-
ing information on the mode of action of these compounds
continues to be investigated yielding clues to the unique prop-
erties of vanadium compounds and provides inspiration for
drug development in diabetes.
Acknowledgments
We thank National Science Foundation under Grant 0628260
(CRC) for funding this work. We thank Dr. P. S. Pharazyn for
editing this chapter.
References
1. Nechay, B. R.; Nanninga, L. B.; Nechay, P. S. E.; Post, R. L.; Grantham, J. J.;Macara, I. G.; Kubena, L. F.; Phillips, T. D.; Nielsen, F. H. Fed. Proc. 1986,45, 123.
Vanadium Biochemistry 339
2. Nielsen, F. H. ACS Symp. Ser. 1998, 711, 297.3. Slebodnick, C.; Hamstra, B. J.; Pecoraro, V. L. Struct. Bonding 1997, 89, 51.4. Crans, D. C.; Smee, J.; Gaidamauskas, E.; Yang, L. Chem. Rev. 2004, 104, 849.5. Crans, D. C. Pure Appl. Chem. 2005, 77, 1497.6. Rehder, D. Angew. Chem. Int. Ed. Engl. 1991, 30, 148.7. Butler, A.; Carter, J. N.; Simpson, M. T. In Vanadium in Proteins and Enzymes;
Bertini, I., Sigel, A., Sigel, H., Eds.; Marcel Dekker: New York, 2001; p 153.8. Rehder, D. Biometals 1992, 5, 3.9. Tracey, A. S., Crans, D. C., Eds.; In Vanadium Compounds: Chemistry,
Biochemistry, and Therapeutic Applications; American Chemical Society:Washington, DC, 1998; Vol. 711.
10. Vilter, H. In Metal Ions in Biological Systems; Sigel, H., Sigel, A., Eds.; MercelDekker, Inc: New York, 1995; Vol. 31, p 325.
11. Butler, A.; Walker, J. V. Chem. Rev. 1993, 93, 1937.12. Colpas, G. J.; Hamstra, B. J.; Kampf, J. W.; Pecoraro, V. L. J. Am. Chem. Soc.
1994, 116, 3627.13. Butler, A.; Baldwin, A. H. Struct. Bonding 1997, 89, 109.14. Butler, A. Coord. Chem. Rev. 1999, 187, 17.15. Butler, A.; Carter-Franklin, J. N. Nat. Prod. Rep. 2004, 21, 180.16. Littlechild, J.; Garcia-Rodriguez, E.; Coupe, E.; Watts, A.; Isupov, M. In Vanadium:
The Verastile Metal; Kustin, K., Pessoa, J. C., Crans, D. C., Eds.; AmericanChemical Society: Washington, 2007; Vol. 974, p 136.
17. Schneider, C. J.; Zampella, G.; DeGioa, L.; Pecoraro, V. L. ACS Symp. Ser. 2007,974, 148.
18. Eady, R. R. In Vanadium in Biological Systems: Physiology and Biochemistry;Chasteen, N. D., Ed.; Kluwer Academic Publishers: Boston, 1990; p 99.
19. Eady, R. R. Chem. Rev. 1996, 96, 3013.20. Antipov, A. N.; Sorokin, D. Y.; L’Vov, N. P.; Kuenen, J. G. Biochem. J. 2003, 369, 185.21. Antipova, A. N.; Lyalikova, N. N.; Khijniak, T. V.; L’Vov, N. P. FEBS Lett. 1998,
441, 257.22. Michibata, H.; Yamaguchi, N.; Uyama, T.; Ueki, T. Coord. Chem. Rev. 2003,
237, 41.23. Ueki, T.; Adachi, T.; Kawano, S.; Aoshima, M.; Yamaguchi, N.; Kanamori, K.;
Michibata, H. Biochim. Biophys. Acta Gene Struct. Expr. 2003, 1626, 43.24. Yamaguchi, N.; Amakawa, Y.; Yamada, H.; Ueki, T.; Michibata, H. Zool. Sci. 2006,
10, 909.25. Yoshihara, M.; Ueki, T.; Yamaguchi, N.; Kamino, K.; Michibata, H. Biochim.
Biophys. Acta Gen. Subj. 2008, 1780, 256.26. Michibata, H.; Uyama, T.; Ueki, T.; Kanamori, K. The Mechanism of Accumulation
and Reduction of Vanadium by Ascidians. Springer-Verlag: Tokyo, 2001.27. Kalk, M. Nature 1963, 198, 1010.28. Bruening, R. C.; Oltz, E. M.; Furukawa, J.; Nakanishi, K.; Kustin, K. J. Am. Chem.
Soc. 1985, 107, 5298.29. Anderson, D. H.; Berg, J. R.; Swinehart, J. H. Comp. Biochem. Physiol. A 1991,
99, 151.30. Smith, M. J.; Kim, D.; Horenstein, B.; Nakanishi, K.; Kustin, K. Acc. Chem. Res.
1991, 24, 117.31. Bayer, E.; Schiefer, G.; Waidelich, D.; Scippa, S.; Devicentiis, M. Angew. Chem.
Int. Ed. Engl. 1992, 31, 52.32. Ryan, D. E.; Ghatlia, N. D.; McDermott, A. E.; Turro, N. J.; Nakanishi, K.; Kustin, K.
J. Am. Chem. Soc. 1992, 114, 9659.33. Smith, M. J.; Ryan, D. E.; Nakanishi, K.; Frank, P.; Hodgson, K. O. Met. Ions Biol.
Syst. 1995, 31, 423.34. Bayer, E.; Kneifel, H. Anorg. Chem. 1973, 85, 542.35. Kneifel, H.; Bayer, E. J. Am. Chem. Soc. 1986, 108, 3075.36. Chasteen, N. D. In Structure and Bonding; Springer-Verlag: New York, 1983;
Vol. 53, p 105.37. Chasteen, N. D. In Biological Magnetic Resonance; Berliner, L., Reuben, J., Eds.;
Plenum Press: New York, 1981; Vol. 3, p 53.38. Chasteen, N. D. Vanadium in Biological Systems: Physiology and Biochemistry.
Kluwer Academic Publishers: Boston, 1990.39. Bilski, J.; McLean, K.; McLean, E.; Soumaila, F.; Lander, M. Int. J. Environ. Sci.
2011, 1, 1033.40. Nriagu, J. O., Ed.; John Wiley & Sons, Inc.: New York, 1998; Vol. 30.41. Nriagu, J. O., Ed.; Vanadium in the Environment. Part 2: Health Effects; John
Wiley & Sons, Inc.: New York, 1998; Vol. 31.42. Butler, A.; Carrano, C. J. Coord. Chem. Rev. 1991, 109, 61.43. Dikanov, S. A.; Liboiron, B. D.; Orvig, C. J. Am. Chem. Soc. 2002, 124, 2969.44. Crans, D. C.; Amin, S. S.; Keramidas, A. D. In Vanadium in the Environment.
Part 1: Chemistry and Biochemistry; Nriagu, J. O., Ed.; John Wiley & Sons, Inc.:New York, 1998; Vol. 30, p 73.
45. Rehder, D. In Multinuclear NMR Spectroscopy; Mason, J., Ed.; Plenum: London,1987; p 479.
46. Kabanos, T. A.; Keramidas, A. D.; Papaioannou, A. B.; Terzis, A. J. Chem. Soc.Chem. Commun. 1993, 643.
47. Crans, D. C.; Trujillo, A. M.; Pharazyn, P. S.; Cohen, M. D. Coord. Chem. Rev.2011, 255, 2178.
48. Manos, M. J.; Tasiopoulos, A. J.; Raptopoulou, C.; Terzis, A.; Woollins, J. D.;Slawin, A. M. Z.; Keramidas, A. D.; Kabanos, T. A. J. Chem. Soc. Dalton Trans.2001, 1556.
49. Berno, P.; Moore, M.; Minhas, R.; Gambarotta, S. Can. J. Chem. 1996, 74, 1930.50. Kimehunt, E.; Spartalian, K.; Holmes, S.; Mohan, M.; Carrano, C. J. J. Inorg.
Biochem. 1991, 41, 125.51. Amin, S. S.; Cryer, K.; Zhang, B.; Sandra, S.; Eaton, ; Anderson, O. P.;
Miller, S. M.; Reul, B. R.; Brichard, S. M.; Crans, D. C. Inorg. Chem. 2000,39, 406.
52. Ballhausen, C. J.; Gray, H. B. Inorg. Chem. 1962, 1, 111.53. Crans, D. C.; Zhang, B.; Gaidamauskas, E.; Keramidas, A. D.; Willsky, G. R.;
Roberts, C. R. Inorg. Chem. 2010, 49, 4245.54. Chatterjee, P. B.; Bhattacharya, S.; Audhya, A.; Choi, K. Y.; Endo, A.;
Chaudhury, M. Inorg. Chem. 2008, 47, 4891.55. Rehder, D. Bull. Mag. Reson. 1982, 4, 33.56. Weidemann, C.; Rehder, D. Inorg. Chim. Acta 1986, 120, 15.57. Rehder, D. In Vanadium in Biological Systems: Physiology and Biochemistry;
Chasteen, N. D., Ed.; Kluwer Academic Publishers: Boston, 1990; p 173.58. Howarth, O. W. Prog. NMR Spectrosc. 1990, 22, 453.59. Butler, A.; Danzitz, M. J.; Eckert, H. J. Am. Chem. Soc. 1987, 109, 1864.60. Elvingson, K.; Fritzsche, M.; Rehder, D.; Pettersson, L. Angew. Chem. Int. Ed.
Engl. 1994, 48, 878.61. Kirk, O.; Conrad, L. S. Angew. Chem. Int. Ed. Engl. 1999, 38, 977.62. van Pee, K. H.; Keller, S.; Wage, T.; Wynands, I.; Schnerr, H.; Zehner, S. Biol.
Chem. 2000, 381, 1.63. Soedjak, H. S.; Butler, A. Biochemistry 1990, 29, 7974.64. Everett, R. R.; Butler, A. Inorg. Chem. 1989, 28, 393.65. Everett, R. R.; Kanofsky, J. R.; Butler, A. J. Biol. Chem. 1990, 265, 4908.66. Neidleman, S. L.; Geigert, J. L. Biohalogenations: Principles, Basic Roles and
Applications. Ellis Horwood: Chichester, 1986; p. 204.67. Tschirret-Guth, R. A.; Butler, A. J. Am. Chem. Soc. 1994, 116, 411.68. Messerschmidt, A.; Wever, R. Proc. Natl. Acad. Sci. U.S.A. 1996, 93, 392.69. Weyand, M.; Hecht, H. J.; Kiess, M.; Liaud, M. F.; Vilter, H.; Schomburg, D.
J. Mol. Biol. 1999, 293, 595.70. Isupov, M. N.; Dalby, A. R.; Brindley, A. A.; Izumi, Y.; Tanabe, T.;
Murshudov, G. N.; Littlechild, J. A. J. Mol. Biol. 2000, 299, 1035.71. Vilter, H. Phytochemistry 1984, 23, 1387.72. Kamenarska, Z.; Taniguchi, T.; Ohsawa, N.; Hiraoka, M.; Itoh, N. Phytochemistry
2007, 68, 1358.73. Wever, R.; Krenn, B. E. In Vanadium in Biological Systems: Physiology and
Biochemistry; Chasteen, N. D., Ed.; Kluwer Academic Publishers: Boston, 1990;p 81.
74. Messerschmidt, A.; Macedo-Ribeiro, S.; Hemrika, W.; Renirie, R.; Wever, R.J. Biol. Inorg. Chem. 1999, 4, 209.
75. Hartung, J.; Dumont, Y.; Greb, M.; Hach, D.; Kohler, F.; Schulz, H.; Casny, M.;Rehder, D.; Vilter, H. Pure Appl. Chem. 2009, 81, 1251.
76. Vilter, H.; Rehder, D. Inorg. Chim. Acta Bioinorg. Chem. 1987, 136, L7.77. Arber, J. M.; Dobson, B. R.; Eady, R. R.; Hasnain, S. S.; Garner, C. D.;
Matsushita, T.; Nomura, M.; Smith, B. E. Biochem. J. 1989, 258, 733.78. Hormes, J.; Kuetgens, U.; Chauvistre, R.; Schreiber, W.; Anders, N.; Vilter, H.;
Rehder, D.; Weidemann, C. Biochim. Biophys. Acta 1988, 856, 293.79. De Boer, E.; Boon, K.; Wever, R. Biochemistry 1988, 27, 1629.80. Littlechild, J.; Rodriguez, E. G.; Isupov, M. J. Inorg. Biochem. 2009, 103, 617.81. Rehder, D. Inorg. Chem. Commun. 2003, 6, 604.82. Vollenbroek, E. G. M.; Simons, L. H.; Vanschijndel, J.; Barnett, P.;
Balzar, M.; Dekker, H.; Vanderlinden, C.; Wever, R. Biochem. Soc. Trans.1995, 23, 267.
83. Van Schijndel, J. W.; Barnet, P.; Roelse, J.; Vollenbroek, E. G.; Wever, R. Eur. J.Biochem. 1994, 225, 151.
84. Chatterjee, P. B.; Mandal, D.; Audhya, A.; Choi, K. Y.; Endo, A.; Chaudhury, M.Inorg. Chem. 2008, 47, 3709.
85. Messerschmidt, A.; Prade, L.; Wever, R. Biol. Chem. 1997, 378, 309.86. Renirie, R.; Charnock, J. M.; Garner, C. D.; Wever, R. J. Inorg. Biochem. 2010,
104, 657.87. de Macedo-Ribeiro, S.; Renirie, R.; Wever, R.; Messerschmidt, A. Biochemistry
2008, 47, 929.88. Hasan, Z.; Renirie, R.; Kerkman, R.; Ruijssenaars, H. J.; Hartog, A. F.; Wever, R.
J. Biol. Chem. 2006, 281, 9738.89. Plass, W. Angew. Chem. Int. Ed. Engl. 1999, 38, 909.
340 Vanadium Biochemistry
90. Messerschmidt, A.; Wever, R. Inorg. Chim. Acta 1998, 273, 160.91. Littlechild, J.; Garcia-Rodriguez, E.; Dalby, A.; Isupov, M. J. Mol. Recognit. 2002,
15, 291.92. Soedjak, H. S.; Butler, A. Biochim. Biophys. Acta 1991, 1079, 1.93. Soedjak, H. S.; Everett, R. R.; Butler, A. J. Ind. Microbiol. 1991, 8, 37.94. Almeida, M.; Filipe, S.; Humanes, M.; Maia, M. F.; Melo, R.; Severino, N.; da
Silva, J. A. L.; Frausto da Silva, J. J. R.; Wever, R. Phytochemistry 2001, 57, 633.95. Molinari, J. E.; Wachs, I. E. J. Am. Chem. Soc. 2010, 132, 12559.96. Zampella, G.; Fantucci, P.; Pecoraro, V. L.; De Gioia, L. J. Am. Chem. Soc. 2005,
127, 953.97. Kravitz, J. Y.; Pecoraro, V. L.; Carlson, H. A. J. Chem. Theor. Comput. 2005,
1, 1265.98. Schneider, C. J.; Zampella, G.; Greco, C.; Pecoraro, V. L.; De Gioia, L. Eur. J.
Inorg. Chem. 2007, 515.99. Hemrika, W.; Renirie, R.; Macedo-Ribeiro, S.; Messerschmidt, A.; Wever, R.
J. Biol. Chem. 1999, 274, 23820.100. Pooransingh-Margolis, N.; Renirie, R.; Hasan, Z.; Wever, R.; Vega, A. J.;
Polenova, T. J. Am. Chem. Soc. 2006, 128, 5190.101. Colpas, G. J.; Hamstra, B. J.; Kampf, J. W.; Pecoraro, V. L. J. Am. Chem. Soc.
1996, 118, 3469.102. Hamstra, B. J.; Colpas, G. J.; Pecoraro, V. L. Inorg. Chem. 1998, 37, 949.103. Zampella, G.; Kravitz, J. Y.; Webster, C. E.; Fantucci, P.; Hall, M. B.;
Carlson, H. A.; Pecoraro, V. L.; De Gioia, L. Inorg. Chem. 2004, 43, 4127.104. Weyand, M.; Hecht, H. J.; Vilter, H.; Schomburg, D. Acta Crystallogr. Sec. D: Biol.
Crystallogr. 1996, 52, 864.105. Rehder, D. Coord. Chem. Rev. 1999, 297.106. Rehder, D.; Schulzke, C.; Dau, H.; Meinke, C.; Hanss, J.; Epple, M. J. Inorg.
Biochem. 2000, 80, 115.107. Feiters, M. C.; Leblanc, C.; Kupper, F. C.; Meyer-Klaucke, W.; Michel, G.;
Potin, P. J. Am. Chem. Soc. 2005, 127, 15340.108. ten Brink, H. B.; Schoemaker, H. E.; Wever, R. Eur. J. Biochem. 2001, 268, 132.109. Ligtenbarg, A. G. J.; Hage, R.; Feringa, B. L. Coord. Chem. Rev. 2003, 237, 89.110. Andersson, M.; Willetts, A.; Allenmark, S. J. Org. Chem. 1997, 62, 8455.111. Wever, R.; ten Brink, H. B.; Tuynman, A.; Dekker, H. L.; Hemrika, W.; Izumi, Y.;
Oshiro, T.; Schoemaker, H. E. Inorg. Chem. 1998, 37, 6780.112. Wever, R.; ten Brink, H. B.; Holland, H. L.; Schoemaker, H. E.; van Lingen, H.
Tetrahedron: Asymmetry 1999, 10, 4563.113. Andersson, M. A.; Allenmark, S. G. Tetrahedron 1998, 54, 15293.114. Wever, R.; ten Brink, H. B.; Dekker, H. L.; Shoemaker, H. E. J. Inorg. Biochem.
2000, 80, 91.115. Werncke, C. G.; Limberg, C.; Knispel, C.; Metzinger, R.; Braun, B. Chem. Eur. J.
2011, 17, 2931.116. Wischang, D.; Hartung, J.; Hahn, T.; Ulber, R.; Stumpf, T.; Fecher-Trost, C. Green
Chem. 2011, 13, 102.117. Nicolai, M.; Goncalves, G.; Natalio, F.; Humanes, M. J. Inorg. Biochem. 2011,
105, 887.118. Salgado, L. T.; Cinelli, L. P.; Viana, N. B.; de Carvalho, R. T.; Mourao, P. A. D.;
Teixeira, V. L.; Farina, M.; Amado, G. M. J. Phycol. 2009, 45, 193.119. Renirie, R.; Dewilde, A.; Pierlot, C.; Wever, R.; Hober, D.; Aubry, J. M. J. Appl.
Microbiol. 2008, 105, 264.120. Hemrika, W.; Renirie, R.; Dekker, H. L.; Barnett, P.; Wever, R. Proc. Natl. Acad. Sci.
U.S.A. 1997, 94, 2145.121. Lindqvist, Y.; Schneider, G.; Vihko, P. Eur. J. Biochem. 1994, 221, 139.122. Stukey, J.; Carman, G. M. Protein Sci. 1997, 6, 469.123. Wever, R.; Renirie, R.; Hemrika, W. J. Biol. Chem. 2000, 275, 11650.124. Neuwald, A. F. Protein Sci. 1997, 6, 1764.125. van de Velde, F.; Arends, I.; Sheldon, R. A. J. Inorg. Biochem. 2000, 80, 81.126. Tanaka, N.; Dumay, V.; Liao, Q. N.; Lange, A. J.; Wever, R. Eur. J. Biochem. 2002,
269, 2162.127. Hales, B. J.; Case, E. E.; Morningstar, J. E.; Dzeda, M. F.; Mauterer, L. A.
Biochemistry 1986, 25, 7253.128. Hales, B. J.; Langosch, D. J.; Case, E. E. J. Biol. Chem. 1986, 261, 15310.129. Howard, J. B.; Rees, D. C. Chem. Rev. 1996, 96, 2965.130. Burgess, B. K.; Lowe, D. J. Chem. Rev. 1996, 96, 2983.131. Blanchard, C. Z.; Hales, B. J. Biochemistry 1996, 35, 472.132. Bishop, P. E.; Jarlenski, D. M. L.; Hetherington, D. R. Proc. Natl. Acad. Sci. U.S.A.
1980, 77, 7342.133. Bishop, P. E.; Jarlenski, D. M. L.; Hetherington, D. R. J. Bacteriol. 1982, 150, 1244.134. Robson, R. L.; Eady, R. R.; Richardson, T. H.; Miller, R. W.; Hawkins, M.;
Postgate, J. R. Nature 1986, 322, 388.135. Hu, Y. L.; Lee, C. C.; Ribbe, M. W. Dalton Trans. 2012, 41, 1118.136. Lee, C. C.; Hu, Y. L.; Ribbe, M. W. Proc. Natl. Acad. Sci. U.S.A. 2009, 106, 9209.137. Rehder, D. J. Inorg. Biochem. 2000, 80, 133.
138. Joerger, R. D.; Loveless, T. M.; Pau, R. N.; Mitchenall, L. A.; Simon, B. H.;Bishop, P. E. J. Bacteriol. 1990, 172, 3400.
139. Robson, R. L.; Woodley, P. R.; Pau, R. N.; Eady, R. R. EMBO J. 1989, 8, 1217.140. Theil, T. J. Bacteriol. 1993, 175, 6269.141. Hu, Y. L.; Ribbe, M. W. Acc. Chem. Res. 2010, 43, 475.142. Arber, J. M.; Dobson, B. R.; Eady, R. R.; Stevens, P.; Hasnain, S. S.; Garner, C. D.;
Smith, B. E. Nature 1987, 325, 372.143. Hales, B. J. T.; Hoffman, A. E.; Brian, M. J. Am. Chem. Soc. 1989, 111, 8519.144. Thorneley, R. N. F.; Bergstrom, N. H. J.; Eady, R. R.; Lowe, D. J. Biochem. J.
1989, 257, 789.145. Lowe, D. J.; Thorneley, R. N. F. Biochem. J. 1984, 224, 895.146. Eady, R. R. Coord. Chem. Rev. 2003, 237, 23.147. Dilworth, M. J.; Loneragan, J. F. New Phytol. 1991, 118, 303.148. Dilworth, M. J.; Eady, R. R. Biochem. J. 1991, 277, 465.149. Hu, Y. L.; Lee, C. C.; Ribbe, M. W. Science 2010, 329, 642.150. Dance, I. Dalton Trans. 2011, 40, 5516.151. Hu, Y.; Lee, C. C.; Ribbe, M. W. Science 2011, 333, 753.152. Yoshiharaa, M.; Ueki, T.; Watanabea, T.; Yamaguchib, N.; Kaminoc, K.;
Michibata, H. Biochim. Biophys. Acta Gene Struct. Expr. 2005, 1730, 206.153. Fukui, K. I.; Ueki, T.; Ohya, H.; Michibata, H. J. Am. Chem. Soc. 2003, 125, 6352.154. Henze, M. Hoppe Seylers Z. Physiol. Chem. 1911, 72, 494.155. Bruening, R. C.; Oltz, E. M.; Furukawa, J.; Nakanishi, K. J. Nat. Prod. 1986, 49,
193.156. Oltz, E. M.; Bruening, R. C.; Smith, M. J.; Kustin, K.; Nakanishi, K. J. Am. Chem.
Soc. 1988, 110, 6162.157. Botte, L.; Scippa, S.; de Vincentiis, M. Experientia 1979, 35, 1228.158. Scippa, S. Acta Zool. 1982, 63, 121.159. Brand, S. G.; Hawkins, C. J.; Marshall, A. T.; Nette, G. W.; Parry, D. L. Comp.
Biochem. Physiol. 1989, 93B, 425.160. Oltz, E. M.; Pollack, S.; Delohery, T.; Smith, M. J.; Ojika, M.; Lee, S.; Kustin, K.;
Nakanishi, K. Experientia 1989, 45, 186.161. Michibata, H.; Hirata, J.; Uesaka, M.; Numakunai, T.; Sakurai, H. J. Exp. Zool.
1987, 244, 33.162. Michibata, H. Zool. Sci. 1996, 13, 489.163. Carlson, R. M. K. Proc. Natl. Acad. Sci. U.S.A. 1975, 72, 2217.164. Robinson, W. E.; Agudelo, M. I.; Kustin, K. Comp. Biochem. Physiol. A 1984,
78, 667.165. Dingley, A. L.; Kustin, K.; Macara, I. G.; McLeod, G. C.; Roberts, M. F. Biochim.
Biophys. Acta 1982, 720, 384.166. Lee, S.; Kustin, K.; Robinson, W. E.; Frankel, R. B.; Spartalian, K. J. Inorg.
Biochem. 1988, 33, 183.167. Kustin, K.; McLeod, G. C.; Gilbert, T. R.; Briggs, L. B. R. Struct. Bonding 1983,
53, 139.168. Vilas Boas, L. V.; Costa Pessoa, J. In Comprehensive Coordination Chemistry.
The Synthesis, Reactions, Properties & Applications of CoordinationCompounds; Wilkinson, G. S., Gillard, R. D., McCleverty, J. A., Eds.; PergamonPress: New York, 1987; Vol. 3, p 453.
169. Frank, P.; Kustin, K.; Robinson, W. E.; Linebaugh, L.; Hodgson, K. O. Inorg.Chem. 1995, 34, 5942.
170. Frank, P.; Hodgson, K. O.; Kustin, K.; Robinson, W. E. J. Biol. Chem. 1998, 273,24498.
171. Frank, P.; Hodgson, K. O. Inorg. Chem. 2000, 39, 6018.172. Frank, P.; Robinson, W. E.; Kustin, K.; Hodgson, K. O. J. Inorg. Biochem. 2001,
86, 635.173. Frank, P.; Carlson, R. M. K.; Carlson, E. J.; Hodgson, K. O. Coord. Chem. Rev.
2003, 237, 31.174. Kustin, K.; Robinson, W. E.; Frankel, R. B.; Spartalian, K. J. Inorg. Biochem.
1996, 63, 223.175. Macara, I. G.; McLeod, G. C. Biochem. J. 1979, 181, 457.176. Macara, I. G.; McLeod, G. C.; Kustin, K. Comp. Biochem. Physiol. A 1979,
62, 821.177. Hirata, J.; Michibata, H. J. Exp. Zool. 1991, 257, 160.178. Samino, S.; Michibata, H.; Ueki, T. Mar. Biotechnol. 2012, 14, 143.179. Frank, P.; Carlson, R. M. K.; Hodgson, K. O. Inorg. Chem. 1986, 25, 460.180. Frank, P.; Hedman, B.; Carlson, R. M. K.; Tyson, T. A.; Roe, A. L.; Hodgson, K. O.
Biochemistry 1987, 26, 4975.181. Tullius, T. D.; Gillum, W. O.; Carlson, R. M. K.; Hodgson, K. O. J. Am. Chem. Soc.
1980, 102, 5670.182. Lee, S.; Nakanishi, K.; Kustin, K. Biochim. Biophys. Acta 1990, 1033, 311.183. Brand, S. G.; Hawkins, C. J.; Parry, D. L. Inorg. Chem. 1987, 26, 627.184. Michibata, H.; Sakurai, H. In Vanadium in Biological Systems: Physiology and
Biochemistry; Chasteen, N. D., Ed.; Kluwer Academic Publishers: Boston, 1990;p 153.
Vanadium Biochemistry 341
185. Bayer, E.; Kneifel, H. Zeit. Fur Nat. Part B 1972, B27, 207.186. Kneifel, H.; Bayer, E. Angew. Chem. Int. Ed. 1973, 12, 508.187. Armstrong, E. M.; Beddoes, R. L.; Calviou, L. J.; Charnock, J. M.; Collison, D.;
Ertok, N.; Naismith, J. H.; Garner, C. D. J. Am. Chem. Soc. 1993, 115, 807.188. Armstrong, E. M.; Collison, D.; Deeth, R. J.; Garner, C. D. J. Chem. Soc. Dalton
Trans. 1995, 191.189. Bayer, E. Met. Ions Biol. Syst. 1995, 31, 407.190. Garner, C. D.; Armstrong, E. M.; Berry, R. E.; Beddoes, R. L.; Collison, D.;
Cooney, J. J. A.; Ertok, S. N.; Helliwell, M. J. Inorg. Biochem. 2000, 80, 17.191. Rehder, D. Chemie in Unserer Zeit 2010, 44, 322.192. ter Meulen, H. Recl. Trav. Chim. Pays. Bas. 1931, 50, 491.193. Bayer, E.; Koch, E.; Anderegg, G. Angew. Chem. Int. Ed. Engl. 1987, 26, 545.194. Berry, R. E.; Smith, P. D.; Harben, S. M.; Helliwell, M.; Collison, D.; Garner, C. D.
Chem. Commun. 1998, 591.195. Smith, P. D.; Harben, S. M.; Beddoes, R. L.; Helliwell, M.; Collison, D.;
Garner, C. D. J. Chem. Soc. Dalton Trans. 1997, 685.196. Smith, P. D.; Cooney, J. J. A.; McInnes, E. J. L.; Beddoes, R. L.; Collison, D.;
Harben, S. M.; Helliwell, M.; Mabbs, F. E.; Mandel, A.; Powell, A. K.; Garner, C. D.J. Chem. Soc. Dalton Trans. 2001, 3108.
197. Yadav, H. S.; Armstrong, E. M.; Beddoes, R. L.; Collison, D.; Garner, C. D.J. Chem. Soc. Chem. Commun. 1994, 605.
198. Ooms, K. J.; Bolte, S. E.; Baruah, B.; Choudhary, M. A.; Crans, D. C.; Polenova, T.Dalton Trans. 2009, 3262.
199. Carrondo, M.; Duarte, M.; Pessoa, J. C.; Silva, J. A. L.; Dasilva, J.; Vaz, M.;Vilasboas, L. F. J. Chem. Soc. Chem. Commun. 1988, 1158.
200. Anderegg, G.; Koch, E.; Bayer, E. Inorg. Chim. Acta 1987, 127, 183.201. Nawi, M. A.; Riechel, T. L. Inorg. Chim. Acta 1987, 136, 33.202. Frausto da Silva, J. J. R.; Guedes Da Silva, M. F. C.; Da Silva, J. A. L.;
Pompeiro, A. J. L.Mol. Electrochem. Inorg. Bioinorg. Organomet. Compd. 1993, 411.203. Bertrand, D. Bull. Am. Museum Nat. Hist. 1950, 94, 407.204. Meisch, H.-U.; Reinle, W.; Schmitt, J. A. Naturwissenschaften 1979, 66, 620.205. da Silva, A. J. L.; Frausto da Silva, J. J. R.; Pombeiro, A. J. L. In Chemistry and
Materials Science, 2012, p 35.206. Berry, R. E.; Armstrong, E. M.; Beddoes, R. L.; Collison, D.; Ertok, S. N.;
Helliwell, M.; Garner, C. D. Angew. Chem. Int. Ed. 1999, 38, 795.207. Johnson, M. D.; Lorenz, B. B.; Wilkins, P. C.; Lemons, B. G.; Baruah, B.;
Lamborn, N.; Stahla, M.; Chatterjee, P. B.; Richens, D. T.; Crans, D. C. Inorg.Chem. 2012, 51, 2757.
208. Lenhardt, J.; Baruah, B.; Crans, D. C.; Johnson, M. D. Chem. Commun. 2006,4641.
209. Lenhardt, J. M.; Baruah, B.; Crans, D. C.; Johnson, M. D. Pure Appl. Chem.2009, 81, 1241.
210. Hubregtse, T.; Hanefeld, U.; Arends, I. Eur. J. Org. Chem. 2007, 2413.211. Aureliano, M.; Henao, F.; Tiago, T.; Duarte, R. O.; Moura, J. J. G.; Baruah, B.;
Crans, D. C. Inorg. Chem. 2008, 47, 5677.212. Pereira, M. J.; Carvalho, E.; Eriksson, J. W.; Crans, D. C.; Aureliano, M. J. Inorg.
Biochem. 2009, 103, 1687.213. Willsky, G. R.; Godzalla, M. E., I.; Kostyniak, P. J.; Chi, L.-H.; Gupta, R.;
Yuen, V. G.; McNeill, J. H.; Mahroof-Tahir, M.; Smee, J. J.; Yang, L.;Lobernick, A.; Watson, S.; Crans, D. C. ACS Symp. Ser. 2007, 974, 93.
214. Reis, P. M.; Silva, J. A. L.; da Silva, J.; Pombeiro, A. J. L. Chem. Commun. 2000,1845.
215. Kirillova, M. V.; Kuznetsov, M. L.; Reis, P. M.; da Silva, J. A. L.; daSilva, J. J. R. F.; Pombeiro, A. J. L. J. Am. Chem. Soc. 2007, 129, 10531.
216. Kirillova, M. V.; Kuznetsov, M. L.; Da Silva, J. A. L.; Da Silva, M. F. C.; DaSilva, J.; Pombeiro, A. J. L. Chem. Eur. J. 2008, 14, 1828.
217. Bertini, L.; Barbieri, V.; Fantucci, P.; De Gioia, L.; Zampella, G. Dalton Trans.2011, 40, 7704.
218. Reis, P. M.; Silva, J. A. L.; Palavra, A. F.; da Silva, J. J. R. F.; Kitamura, T.;Fujiwara, Y.; Pombeiro, A. J. L. Angew. Chem. Int. Ed. 2003, 42, 821.
219. Geethalakshmi, K. R.; Waller, M. P.; Buhl, M. Inorg. Chem. 2007, 46, 11297.220. Remenyi, C.; Munzarova, M. L.; Kaupp, M. J. Phys. Chem. B 2005, 109, 4227.221. Ishii, T.; Nakai, I.; Numako, C.; Okoshi, K.; Otake, T. Naturwissenschaften 1993,
80, 268.222. Ishii, T.; Otake, T.; Okoshi, K.; Nakahara, M.; Nakamura, R. Marine Biol. 1994,
121, 143.223. Ishii, T.; Nakai, I. In Metal Ions in Biological Systems; Sigel, H., Sigel, A., Eds.;
Marcel Dekker, Inc.: New York, 1995; Vol. 31, p 491.224. Ishii, T. In Vanadium in the Environment. Part 1: Chemistry and Biochemistry;
Nriagu, J. O., Ed.; John Wiley and Sons, Inc.: New York, 1998; Vol. 30, p 199.225. Willsky, G. R.; Chi, L.-H.; Godzalla, M. E., III; Kostyniak, P. J.; Smee, J. J.;
Crans, D. C.; Trujillo, A. M.; Alfano, J. A.; Ding, W.; Hu, Z. Coor. Chem. Rev.2011, 19–20, 2258–2269.
226. Shechter, Y.; Elberg, G.; Shisheva, A.; Gefel, D.; Sekar, N.; Qian, S.; Bruck, R.;Gershonov, E.; Crans, D. C.; Goldwasser, Y.; Fridkin, M.; Li, J. In ACSSymposium Series, 1998, p 308.
227. Shechter, Y. Lett. Pept. Sci. 1998, 5, 319.228. Shechter, Y.; Li, J.; Meyerovitch, J.; Gefel, D.; Bruck, R.; Elberg, G.; Miller, D. S.;
Shisheva, A. Mol. Cell. Biochem. 1995, 153, 39.229. Shechter, Y.; Karlish, S. J. D. Nature 1980, 284, 556.230. Sakurai, H.; Tsuchiya, K.; Nukatsuka, M.; Kawada, J.; Ishikawa, S.; Yoshida, H.;
Komatsu, M. J. Clin. Biochem. Nutr. 1990, 8, 193.231. Watanabe, H.; Nakai, M.; Komazawa, K.; Sakurai, H. J. Med. Chem. 1994, 37, 876.232. Sakurai, H.; Fujii, K.; Watanabe, H.; Tamura, H. Biochem. Biophys. Res. Commun.
1995, 214, 1095.233. Hiromura, M.; Nakayama, A.; Adachi, Y.; Doi, M.; Sakurai, H. J. Biol. Inorg. Chem.
2007, 12, 1275.234. Karmaker, S.; Saha, T. K.; Yoshikawa, Y.; Sakurai, H. Chem. Med. Chem. 2007, 2,
1607.235. McNeill, J. H.; Yuen, V. G.; Hoveyda, H. R.; Orvig, C. J. Med. Chem. 1992, 35,
1489.236. Cam, M. C.; Cros, G. H.; Serrano, J. J.; Lazaro, R.; McNeill, J. H. Diab. Res. Clin.
Pract. 1993, 20, 111.237. Caravan, P.; Gelmini, L.; Glover, N.; Herring, F. G.; Li, H.; McNeill, J. H.;
Rettig, S. J.; Setyawati, I. A.; Shuter, E.; Sun, Y.; Tracey, A. S.; Yuen, V. G.;Orvig, C. J. Am. Chem. Soc. 1995, 117, 12759.
238. Yuen, V. G.; Caravan, P.; Gelmini, L.; Glover, N.; McNeill, J. H.; Setyawati, I. A.;Zhou, Y.; Orvig, C. J. Inorg. Biochem. 1997, 68, 109.
239. Poucheret, P.; Verma, S.; Grynpas, M. D.; McNeill, J. H. Mol. Cell. Biochem.1998, 188, 73.
240. Melchior, M.; Thompson, K. H.; Jong, J. M.; Rettig, S. J.; Shuter, E.; Yuen, V. G.;Zhou, Y.; McNeill, J. H.; Orvig, C. Inorg. Chem. 1999, 38, 2288.
241. Willsky, G. R.; Goldfine, A. B.; Kostyniak, P. J.; McNeill, J. H.; Yang, L. Q.;Khan, H. R.; Crans, D. C. J. Inorg. Biochem. 2001, 85, 33.
242. Thompson, K. H.; Lichter, J.; LeBel, C.; Scaife, M. C.; McNeill, J. H.; Orvig, C.J. Inorg. Biochem. 2009, 103, 554.
243. Thompson, K. H.; Orvig, C. J. Inorg. Biochem. 2006, 100, 1925.244. Fantus, I. G.; Kadota, S.; Deragon, G.; Foster, B.; Posner, B. I. Biochemistry 1989,
28, 8864.245. Posner, B. I.; Shaver, A.; Fantus, I. G. In New Antidiabetic Drugs; Bailey, C. J.,
Flatt, P. R., Eds.; Chapter 8, Smith-Gordon: London, 1990, p 107.246. Posner, B. I.; Faure, R.; Burgess, J. W.; Bevan, A. P.; Lachance, D.; Zhang-
Sun, G.; Fantus, I. G.; Ng, J. B.; Hall, D. A.; Lum, B. S.; Shaver, A. J. Biol. Chem.1994, 269, 4596.
247. Bevan, A. P.; Burgess, J. W.; Yale, J.-F.; Drake, P. G.; Lachance, D.; Baquiran, G.;Shaver, A.; Posner, B. I. Am. J. Physiol. 1995, 268, E60.
248. Bevan, A. P.; Drake, P. G.; Yale, J. F.; Shaver, A.; Posner, B. I.Mol. Cell. Biochem.1995, 153, 49.
249. Shaver, A.; Hall, D. A.; Ng, J. B.; Lebuis, A.-M.; Hynes, R. C.; Posner, B. I. Inorg.Chim. Acta 1995, 229, 253.
250. Shaver, A.; Ng, J. B.; Hall, D. A.; Posner, B. I. Mol. Cell. Biochem. 1995, 153, 5.251. Sekar, N.; Li, J. P.; Shechter, Y. Crit. Rev. Biochem. Mol. Biol. 1996, 31, 339.252. Yu, Z. W.; Jansson, P. A.; Posner, B. I.; Smith, U.; Eriksson, J. W. Diabetologia
1997, 40, 1197.253. Posner, B. I.; Yang, C. R.; Shaver, A. ACS Symp. Ser. 1998, 711, 316.254. Rehder, D.; Pessoa, J. C.; Geraldes, C. F. G. C.; Castro, M. M. C. A.; Kabanos, T.;
Kiss, T.; Meier, B.; Micera, G.; Pettersson, L.; Rangel, M.; Salifoglou, A.; Turel, I.;Wang, D. J. Biol. Inorg. Chem. 2002, 7, 384.
255. Delgado, T. C.; Tomaz, A. I.; Correia, I.; Pessoa, J. C.; Jones, J. G.; Geraldes, C.;Castro, M. J. Inorg. Biochem. 2005, 99, 2328.
256. Roess, D. A.; Smith, S. M. L.; Winter, P.; Zhou, J.; Dou, P.; Baruah, B.;Trujillo, A. M.; Levinger, N. E.; Yang, X.; DBarisas, B. G.; Crans, D. C. Chem.Biodivers. 2008, 5, 1558.
257. Smee, J. J.; Epps, J. A.; Ooms, K.; Bolte, S. E.; Polenova, T.; Baruah, B.; Yang, L.;Ding, W.; Li, M.; Willsky, G. R.; Cour, A. L.; Anderson, O. P.; Crans, D. C. J. Inorg.Biochem. 2009, 103, 575.
258. Buglyo, P.; Crans, D. C.; Nagy, E. M.; Lindo, R. L.; Yang, L.; Smee, J. J.;Wenzheng, J.; Chi, L.-H.; Godzalla, M. E., III; Willsky, G. R. Inorg. Chem. 2005,44, 5416.
259. Zorzano, A.; Palacin, M.; Marti, L.; Garcia-Vicente, S. J. Inorg. Biochem. 2009,103, 559.
260. Cheatham, B.; Vlahos, C. J.; Cheatham, L.; Wang, L.; Blenis, J.; Kahn, C. R. Mol.Cell. Biol. 1994, 14, 4902.
261. Goldfine, A. B.; Willksy, G.; Kahn, C. R. In Vanadium Compounds: Biochemistry,Chemistry, and Therapeutic Applications; Tracey, A. S., Crans, D. C., Eds.;American Chemical Society: Washington, DC, 1998; p 353.
342 Vanadium Biochemistry
262. Saltiel, A. R.; Kahn, A. R. Nature 2001, 414, 799.263. Begum, N.; Draznin, B. J. Clin. Invest. 1992, 90, 1254.264. Jacqes-Camarena, O.; Gonzalez-Ortiz, M.; Martinez-Abundis, E.;
Lopez-Madrueno, J. F. P.; Medina-Santillan, R. Ann. Nutr. Metab. 2008, 53, 195.265. McNeil, J. H.; Yuen, V. G.; Hoveyda, H. R.; Orvig, C. J. Med. Chem. 1992, 35,
1489.266. Orvig, C.; McNeill, J. H.; Vasilevskis, J. In Metal Ions in Biological
Systems; Sigel, H., Sigel, A., Eds.; Marcel Dekker, Inc.: New York, 1995; Vol. 31,p 575.
267. McNeill, J. H.; Orvig, C. In McNeill et al. The University of Brisith Columbia,Vancouver, Canada: United States, 1996.
268. Sun, Y.; James, B. R.; Rettig, S. J.; Orvig, C. Inorg. Chem. 1996, 35, 1667.269. Bordbar, A. K.; Creagh, A. L.; Mohammadi, F.; Haynes, C. A.; Orvig, C. J. Inorg.
Biochem. 2009, 103, 643.270. Scott, L. E.; Orvig, C. Chem. Rev. 2009, 109, 4885.271. Thompson, K. H.; Orvig, C. Dalton Trans. 2006, 761.272. Liboiron, B. D.; Thompson, K. H.; Hanson, G. R.; Lam, E.; Aebischer, N.; Orvig, C.
J. Am. Chem. Soc. 2005, 127, 5104.273. Monga, V.; Thompson, K. H.; Yuen, V. G.; Sharma, V.; Patrick, B. O.;
McNeill, J. H.; Orvig, C. Inorg. Chem. 2005, 44, 2678.274. Nakai, M.; Sekiguchi, F.; Obata, M.; Ohtsuki, C.; Adachi, Y.; Sakurai, H.; Orvig, C.;
Rehder, D.; Yano, S. J. Inorg. Biochem. 2005, 99, 1275.275. Saatchi, K.; Thompson, K. H.; Patrick, B. O.; Pink, M.; Yuen, V. G.; McNeill, J. H.;
Orvig, C. Inorg. Chem. 2005, 44, 2689.276. Thompson, K. H.; Liboiron, B. D.; Sun, Y.; Bellman, K. D. D.; Setyawati, I. A.;
Patrick, B. O.; Karunaratne, V.; Rawji, G.; Wheeler, J.; Sutton, K.; Bhanot, S.;Cassidy, C.; McNeill, J. H.; Yuen, V. G.; Orvig, C. J. Biol. Inorg. Chem. 2003,8, 66.
277. Huyer, G.; Liu, S.; Kelly, J.; Moffat, J.; Payette, P.; Kennedy, B.; Tsaprailis, G.;Gresser, M. J.; Ramachandran, C. J. Biol. Chem. 1997, 272, 843.
278. Li, M.; Ding, W. J.; Baruah, B.; Crans, D. C.; Wang, R. L. J. Inorg. Biochem. 2008,102, 1846.
279. Yuan, C. X.; Lu, L. P.; Wu, Y. B.; Liu, Z. W.; Guo, M. L.; Xing, S.; Fu, X. Q.;Zhu, M. L. J. Inorg. Biochem. 2010, 104, 978.
280. McLauchlan, C. C.; Hooker, J. D.; Jones, M. A.; Dymon, Z.; Backhus, E. A.;Greiner, B. A.; Dorner, N. A.; Youkhana, M. A.; Manus, L. M. J. Inorg. Biochem.2010, 104, 274.
281. Lu, L. P.; Gao, X. L.; Zhu, M. L.; Wang, S. L.; Wu, Q.; Xing, S.; Fu, X. Q.;Liu, Z. W.; Guo, M. L. Biometals 2012, 25, 599.
282. Pessoa, J. C.; Tomaz, I. Curr. Med. Chem. 2010, 17, 3701.283. Sanna, D.; Micera, G.; Garribba, E. Inorg. Chem. 2009, 48, 5747.284. Sanna, D.; Micera, G.; Gabellieri, E. Inorg. Chem. 2010, 49, 174.285. Sanna, D.; Buglyo, P.; Micera, G.; Garribba, E. J. Biol. Inorg. Chem. 2010, 15, 825.286. Sanna, D.; Micera, G.; Gabellieri, E. Inorg. Chem. 2011, 50, 3717.287. Correia, I.; Jakusch, T.; Cobbinna, E.; Mehtab, S.; Tomaz, I.; Nagy, N. V.;
Rockenbauer, A.; Pessoa, J. C.; Kiss, T. Dalton Trans. 2012, 41, 6477.288. Iglesias-Gonzalez, T.; Sanchez-Gonzalez, C.; Montes-Bayon, M.; Llopis-
Gonzalez, J.; Sanz-Medel, A. Anal. Bioanal. Chem. 2012, 402, 277.289. Sanna, D.; Biro, L.; Buglyo, P.; Micera, G.; Garribba, E. Metallomics 2012, 4, 33.290. Li, M.; Smee, J. J.; Ding, W.; Crans, D. C. J. Inorg. Biochem. 2009, 103, 585.291. Smee, J. J.; Epps, J. A.; Ooms, K.; Bolte, S.; Polenova, T.; Baruah, B.; Yang, L.;
Ding, W.; Li, M.; Willsky, G. R.; la Cour, A.; Anderson, O. P.; Crans, D. C. J. Inorg.Biochem. 2009, 103, 575.
292. Li, M.; Ding, W.; Smee, J. J.; Baruah, B.; Willsky, G. R.; Crans, D. C. BioMetals2009, 103, 585.
293. Yang, X.; Wang, K.; Lu, J.; Crans, D. C. Coord. Chem. Rev. 2003, 237, 103.294. Crans, D. C.; Schoeberl, S.; Gaidamauskas, E.; Baruah, B.; Roess, D. A. J. Biol.
Inorg. Chem. 2011, 16, 961.295. Winter, P. W.; Al-Qatati, A.; Wolf-Ringwall, A. L.; Schoeberl, S.; Chatterjee, P. B.;
Barisas, B. G.; Roess, D. A.; Crans, D. C. Dalton Trans. 2012, 41, 6419.