Journal of Inorganic Biochemistry 86 (2001) 221

Synthesis and characterisation of polynuclear copper(II) complexes of 1,3-tpbd

Simon P. Foxon and Siegfried Schindler Institute of Inorganic Chemistry, University of Erlangen-Niirnberg, Egerlandstrasse 1, 91058 Erlangen, GERMANY (e-mail: foxon@anorganik, uni-erlangen, de)

The motivation for the design, synthesis and characterisation of binuclear copper complexes lies foremost in the elucidation of the intimate relationship between metalloenzyme function and active site structure. In this regard, the ligand 1,3-tpbd {tpbd = 1,3-bis[bis(2- pyridylmethyl)amino]benzene} has been found to be a versatile ligand in the synthesis of AA. dinuclear copper complexes that can be regarded as model complexes for the copper % ~ "N N" ~ J proteins hemocyanin and tyrosinase.1 ~ Moreover, interest in the preparation and characterisation of polynuclear copper(II) complexes derives from the efforts to understand the factors that are responsible for the magnetic exchange interactions 2 between coupled metal centres. Much attention has been focused on magnetostructural correlations and the exchange mechanism involving different bridging groups (eg. oxalate, azide, etc.) between the copper(II) centres. Several examples of structurally characterised bridged dinuclear copper(II) complexes of 1,3-tpbd as tigand will be presented.

1. Schindler S., Szalda D.J. and Creutz C, J. Inorg. Chem., 31, 2255-2264 (1992) 2. Kahn O., Angew. Chem., Int. Ed., 24, 834-850 (1985)

Reductase of ferredoxin in benzene dioxygenase system

Leonidas Fragkos- Livanios a, Jeremy R. Mason b Ph.D. student in Microbiology, Division of Life Sciences, School of Health & Life Sciences, King's College London, University of London, 150 Stamford str, Frankling-Wilkins Building SE1 9NN, London, UK. (e-mail: leonidas.fragos-livanios@kcl, ac. uk).

~' Head of Division of Life Sciences, School of Health & Life Sciences, King's College London, University of London, 150 Stamford str, Frankling-Wilkins Building SE1 9NN, London, UK.

Benzene dioxygenase (BED) from Pseudomonas putida ML2 is a three-component enz)nne which catalyses the oxidation of benzene to cis-1,2-dihydroxy-cyclohexa-3,5-diene. The three components of the enzyme are: reductaseBzD, ferredoxinBED and the catalytic terminal oxygenase, ISPBED, which is composed of two subunits, c~ and 13, in a c~2132 configuration. The first component, reductase, is a flavoprotein which catalyses the transfer of two electrons from NADH to the following redox component, ferredoxinBED, through which the electrons are transferred to ISPBED. The reductaseBzD was purified from E.coli JMI09pJRM503, in which the genes encoding reductaseBED and ferredoXinBZn, bedA and bedB respectively, are expressed. DEAE deionizing and gel filtration chromatography were used for this purification. Despite its sensitivity, the enzyme acquired was active. The bedA and bedB genes were also expressed in a polyhistidine tag vector (pHAT10) for fast, one-step puriffication using Immobilized Metal Ion Affinity Chromatography. Parallel to that, kinetic studies on a stable complex of reductaseBzD and ferredoxinBZD are presented. Cross-linking techniques are being used for the generation of that complex. The aim of this series of experiments is to determine the electron transfer mechanism from reductaseBED to ISPBED through ferredoxinB~O, clarifying the role of ferredoxinBzD (shuttle electron carrier or intermediate of a three-component complex). The identification of the proteins is made with Western blotting. For the determination of reductaseBED structure, the purified protein used to generate reductaseBED crystals have been generated (sitting drop, hanging drop, paraffin-silicon oil technique). The relevant crystallographic experiments are still in progress.

This work is supported by "ALEXANDROS S. ONASIS" beneficial foundation. Athens. Greece.

222 Journal of lnorgenic Biochemistry 86 (2001)

Polypeptide motifs for metal-ion binding and fluorescence sensing

Katherine J. Franz, Dierdre A. Pearce and Barbara Imperiali Department of Chemistry, Massachusetts Institute of Technology Cambridge, MA 02139 (e-mail. kfranz@mit, edu)

The modular nature of polypeptides makes them enticing tools for constructing fluorescent metal-ion sensors. We have employed two general strategies in this area, the first being the incorporation of a reporter element, usually an unnatural, fluorogenic amino acid, into a peptide sequence that selectively binds and signals a specific metal ion analyte. A variety of peptidyl sensors have been synthesized for sensing Cu 2+, Zn 2+, Ni z+ and Fe 3+. The second strategy uses the metal ion itself, for example Tb 3÷, as the reporting element and the peptide architecture for subsequent recognition events.

metal ion recognition ~ . ~ , , , . ~ ( p e p t i d e ) ~

Fluorescent reporter

In both of these strategies, the metal-binding residues can be tailored by incorporating native metal-binding amino acids such as glutamate, aspartate, histidine and cysteine, or by introducing unnatural amino acids with desirable functionality. The architecture of the peptide itself can also be engineered to tune various properties of the final sensor. For instance, a sequence containing a Zn-binding hydroxyquinoline unit and a cysteine on opposite sides of a 13 turn provides sensors with high Zn-affinity if a tight turn is used, or with lower affinity if a weak turn is used in the peptide backbone.

Because the sensors are built with amino acid building blocks, these constructs are amenable to combinatorial synthesis and high through-put screening technologies. We have recently used this strategy to identify sequences based on Ca2+-binding loops that are optimized for sensitizing Tb 3+ emission.

K.J.F. acknowledges the National Institutes of Health for fellowship support.

Relevance of alkali metal ions for the formation of thymine quartet structures: an X-ray study

E v a F re i s inge r a'b, B e r n h a r d L ippe r t a

Department of Chemistry, University of Dortmund, Otto-Hahn Strasse 6, 44221 Dortmund, Germany

b Present address. Department of Pharmacological Sciences, SUNY Stony Brook, Stony Brook, NY 11 794, USA (e-mail: freisinger@pharm.sunysb, edu)

Binding of the alkali metal ions Na ÷ and K + to nncleobase sites such as G-O6, T-O4 or U-O4 is known to be crucial for the formation and stabilization of nucleobase quartets in tetrastranded nucleic acid structures and substructures (G4, T4, U4). Examples for quartet structures of model nucleobases are, to the best of our knowledge, limited to two X-ray structures of a (1-MeUH)4 (1-MeUH = 1-methyluracil) motif. 1 With the motivation to crystallize a similar thymine quartet we investigated the influence of the alkali metal ions Na ÷, K +, Rb + and Cs ÷ as well as Mg 2÷ and accidentally also H502 + on the crystallization of 1-Ethylthymine (1-EtTH). 2 Our trials yielded a number of compounds, only those relevant for thymine quartet formation analogous to those structures in tetrastranded nucleic acids will be presented here.

2 6 S - 2 8 7 A

1. Witkowski H., Freisinger E. and Lippert B., Chem. Commun., 1315 - 1316 (1997) 2. Freisinger E., Schimanski A. and Lippert B., J. Biol. Inorg. Chem., 6, 378 - 389 (2001)

The Fonds der Chemischen Industrie and the Deutsche Forschungsgemeinschaft are acknowledged for financial support.

Journal of Inorganic Biochemistry 86 (2001) 223

RPE and electrochemical studies of nickel (II) tetraazaannulene complexes

Geraldo Roberto Friedermann, Shirley Nakagaki, Antonio S~lvio Mangrich, Jos6 Mauricio Caiut, Rodrigo de Araujo Franga Departamento de Quimica, Universidade Federal do Parand, Centro PolitOcnico, C.P. 19081,

CEP 81531990, Curitiba, Parand, Brasil (e-mail: grf@quimica.ufpr, br) ]

The metal tmtaa(dianion of 6,8,15,17-tetramethyl-5-14-dibenzo[b,i][1,4,8,11] - ~ / ~ , ~ I R tetraaza-cyclotetradecine) complex (Fig.) has been used as active sites of model of "ff "~'T" metallo-enzimes in biological systems I. In this work Ni(II)-tmtaa and derivated c/'-~'cC'~'r"N\ / N ~ compounds studied by EPR to investigate the capacity of these compounds to be x - ~ ) J . . . Ni ++ w a s

good model compounds. The EPR signal in g~-2,01, A~25G was observed to the Ni- "." , , , N / \N- -.I compounds and increase with time stabilizing after ca. 100 days. The signal has been attributed to a formation of radical specie 2. Cyclic Voltametric studies in old-Ni(II) R

X=H, C1, 2C1, CH 3 complexes shown a new non-reversible signal at ~ -1.6 vs. NHE. Electrochemical R=CH 3, CCH 2(CH 3)2 reduction of fresh Ni(II) compounds at - 1.9 V vs. NHE, produced Ni(I) EPR spectra (at 77K), suggesting that the reduction process occurs on metallic center. In order to investigate the redox potentials of these dibenzo-tetraazaannulene derivates, we made a systematic study of the effect that the changing in the ligand structure causes on redox properties. We elaborated a simple method to predict the redox potentials of new complexes without synthesize them. We observed that each chlorine atom in the benzenoid rings of the ligand increase the redox potential about 100mV and the exchange of methyl group by isobuthyl in R causes an increase of 20-40 mV in this property. Same effects were observed when these ligands were complexed with other transition metals (Cu, Co, Mn).

1. Arai T., Kashitani K., Kondo H., Sakaki S., Chem. Soc. Japan, 67, 705-709 (1994). 2. Renner M.W., Furenlid L.R., Brakigia K.M, Forman A., Shin, H.K., Simpson n.J., Smith, K.M., Fajer J.,

J.Am.Chem. Soc., 113:18, 6891-6898 (1991).

We acknowledg: UFPR, CAPES, CNPq, LACTEC, FUNPAR, PADCT.

Synthetic pathway to new targeting MRI contrast agents

Luca Frullano a, Jan Rohovec, b, Joop A. Peters a "Department of Applied Organic Chemistry and Catalysis, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands (e-mail." L.Frullano@tnw. tudelft, nl) bDepartment of Inorganic Chemistry, Charles University, Hlavova 2030, Prague 12840, Czech Republic

Nowadays the challenge in the design of MRI Contrast Agents is represented by the development of new targeting agents. Among the various possible targets, oligosaccharides are of a particular interest because they play a prominent role in several diseases like diabetes or cancer.

Herein we report the synthetic details of different DTPA-like chelating agents for lanthanide ions designed to give rise to a bifunctional interaction with particular type of sugars, through a boronic and a guanidinium or amino moiety. In particular, the boronic function is known to form stable complexes with vicinal cis diols present in saccharides, in non aqueous media or basic aqueous media and the second group is introduced to produce an interaction with basic sites present on the target sugar.

I. Tony D. James, K.R.A. Samankumara and Seiji Shinkai, Angew. Chem. Int. Ed. Engl., 35, 1910- 1922 (1996) 2. John. J. Lavigne and Eric V. Anslyn, Angew. Chem. Int. Ed. Engl., 38, 3666-3669 (1999)

224 Journal of Inorganic Biochemistry 86 (2001)

Synthes i s and character izat ion of high valent iron p o r p h y r i n complexes as mode l s for react ion intermediates of c y t o c h r o m e c oxidase

Hiroshi Fujii a,b Yumiko Fumoto c, Noboru Ono c a Center for Integrative Bioscience, Okazaki National Research Institutes, Myodaiji, Okazaki

444-8585, Japan, (e-mail. hiro@ims.ac.jp) b Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan c Department of Chemistry, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan

Cytochrome c oxidase (CcO) is the terminal oxidase that reduces molecular oxygen to water, coupling with proton pumping across the mitochondrial inner membrane. Since discovery of this enzyme, many structural and functional studies have been done to understand its reaction mechanism. Recent X-ray analyses reveal that this enzyme contains a binuclear center, heme-a3-CuB site, as a reaction site. The binuclear center of the resting enzyme is ferric/cupric form. The binuclear active site is reduced to a ferrous/cuprous form by two electrons from cytochrome c through the CUA and heme a site. The ferrous/cuprous form of active site reacts with 02 to yield an internal dioxygen adduct, intermediate A state, which is further converted to intermediate P and F by the

~ s

Mes~~ I )Fe~i~N~ CH3 OHC~Mes

aid of the electrons and protons. Although the intermediates P and F have been studied by resonance Raman and flash- flow absorption spectroscopies, the electronic states of these intermediates are not still clear. To reveal the electronic states of these intermediates and to understand the reaction mechanism of CcO, we have synthesized model complexes of the heine-a3 site of cytochrome c oxidase. The model complex contains a formyl group at pyrrole-[3 position to mimic the heme a3 and mesityl groups to stabilize high valent oxo iron species (see Figure). We have succeeded in the preparation of a high valent oxo iron porphyrin complex as a model for the intermediate P by the oxidation of the ferric model complex with mCPBA or ozone. In this poster, we will present the electronic structure of this high valent oxo iron porphyrin complex and also discuss the reaction mechanism of CcO.

Introduction of tetrahedral distortion to copper complexes by using (-)-sparteine and its effect on the oxygen adduct format ion

Yasuhiro Funhashi a, Mitsumi Kishida a, Kaori Nakaya b, Shun Hirota b, Osamu Yamauchi c, Koichiro Jitsukawa a, Hideki Masuda a "Department of Applied Chemistry, Faculty of Engineering, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, JAPAN (e-mail.funa@ach.nitech.ac.jp) bDepartment of Chemistry, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, JAPAN bUnit of Chemistry, Faculty of Engineering, Kansai University, Yamate-cho, Osaka, 464-8602, JA PAN

Extensive studies on the dinuclear Cu-dioxygen complexes as biomimetic model of oxyhemocyanin revealed the presence of the interconversion between ,u-r/2:q2-peroxodicopper(II) and bis(,u-oxo) dicopper(III) cores. The M2(,u-O)2 complexes so far reported substantially had a planar 'diamond' structure, which has been regarded as an important motif of Q-activating intermediate induced by dimetal center in biological systems. In this study, we tried to introduce a teterahedral distortion to a bis(fl-hydroxo)-bridged dinuclear copper(II) complex, and synthesized a Cumz(p-O)2 core by using (-)-sparteine (Sp) as a bidentate ligand. The crystal structure of [(Sp)zCuIIz(OH)2](C104)2 (1) exhibited that the two Cu(II) centers form a hydroxo-bridged M2(fl-OH)2 core structure, where each Cu(II) geometry is tetrahedrally distorted and the two coordination planes are twisted. Addition of O2 into CH2Clz solution of [Cu I (Sp)(CH3CN) 2]CF3S03 (2) at -80 °C gave a yellow-brown species of [(Sp)2CumzO2] 2+ (3), which shows intense absorption bands at ~-m~x (e / M" cm ~ (2Cu)-i) = 330 nm (12500) and 427 nrn (22800) and the resonance Raman band at 619/591 cm q when ~602/~802 is used. Relationships between these structures and spectroscopic features will be discussed in detail.

(sp)

Journal of Inorganic Biochemistry 86 (2001) 225

The roles of CoASH in the pyruvate:ferredoxin oxidoreductase reaction mechanism: rate enhancement by CoASH of electron transfer from a radical

intermediate to an iron-sulfur cluster

Cristina Furdui, Stephen W. Ragsdale Department of Biochemistry, University of Nebraska, Nl16 Beadle Center, 68588-0664, Lincoln, Nebraska, USA (e-mail: cfurdui@unlserve.unl, edu)

Pyruvate:ferredoxin oxidoreductase (PFOR) catalyzes the CoASH-dependent oxidative decarboxylation of pyruvate and the synthesis of pyruvate from acetyl-CoA and CO2. In autotrophic anaerobes, such as methanogenic Archaea and acetogenic bacteria, these reactions link the Wood-Ljungdahl pathway of autotrophic growth to glycolysis and to cell carbon synthesis. The PFOR reaction mechanism involves a substrate-derived radical intermediate, called the hydroxyethyl-thiamine pyrophosphate (HE-TPP) intermediate that forms rapidly after PFOR reacts with pyruvate. Oxidative decay of the HE-TPP radical is strictly linked to reduction of an intramolecular [4Fe-4S] cluster. In the presence of CoASH, this redox reaction occurs 10 5 -fold faster than in its absence. While in the absence of CoASH, the reaction is a true electron transfer characterized by a very slow rate, in the presence of CoASH it becomes gated by an yet-unknown adiabatic event. The origin of this rate enhancement is mainly entropy related and the predominant component of this rate enhancement is the thiol group of CoASH. There does not appear to be any evidence that the binding energy of CoASH is transformed to catalytic power by Jenck's "Circe effect". We conclude that CoASH itself is a part of the covalent electron transfer pathway between the HE-TPP radical intermediate and the FeS cluster. This would be the first example of a protein electron tunneling in which the pathway for the electron transfer does not reside on the protein structure but on the cofactor/substrate structure.

Spectral and kinetic studies on the formation of eosinophil peroxidase compound I and its reaction with one- and two-electron donors

Paul G e o r g Fur tmiJ l ler a, W a l t e r J a n t s c h k o a, Chr i s t i an O b i n g e r a

~lnstitute of Chemistry, University of Agricultural Sciences, Muthgasse 18, A-1190 Vienna, Austria, Fax." +43-1-36006-6059," (e-mail: cobinger@edv2.boku.ac.a 0

Eosinophil peroxidase, the major granule protein in eosinophils, is the least studied human peroxidase. Here, we have performed spectral and kinetic measurements to study the nature of its redox intermediate compound I which takes part in both the peroxidation and the halogenation reaction. This study presents transient kinetic measurements of the formation of compound I of human eosinophil peroxidase (EPO) and its reaction with halides, thiocyanate, ascorbate and tyrosine using the sequential-mixing stopped-flow technique. Addition of one equivalent of hydrogen peroxide to native EPO leads to complete formation of compound I. At pH 7 and 15°C the apparent second-order rate constant is (4.3 + 0.4) × 10 7 M "1 s "1. The rate for compound I formation by hypochlorous acid is (5.6 + 0.7) x 10 7 M 1 sk EPO compound I is unstable and decays to a stable intermediate with a compound II-like spectrum. At pH 7 the two-electron reduction of compound I to the native enzyme by thiocyanate has a second-order rate constant of(1.0 + 0.5) × 10 8 M -I s'k Iodide [(9.3 _+ 0.7) x 10 7 M -l S "l] is shown to be a better electron donor than bromide [(1.9 + 0.1) x 10 7 M t sq], whereas chloride oxidation by EPO compound I is extremely slow [(3.1 + 0.3) x 10 3 M 1 st]. The pH dependence studies suggest that a protonated form of compound I is more competent in oxidizing the anions. In the presence of ascorbate or tyrosine compound I is reduced to compound II with a second-order rate constant of(1.0 + 0.2) × 10 6 M t s ~ and (3.5 + 0.2) × 10 5 M ~ s ~, respectively (pH 7, 15°C). The results are discussed in comparison with those of the homologous peroxidases myeloperoxidase and lactoperoxidase and with respect to the role of EPO in host defence and tissue injury.

226 Journal of Inorganic Biochemistry 86 (2001)

Structural and dynamical features of the lincomycin-Cu(II) complex in water solution

N i c o l a Gagge l l i a, E l e n a G a g g e l l i a, D a n i e l a V a l e n s i n a, Giann i V a l e n s i n a, M a t g o r z a t a J e 2 o w s k a - B o j c z u k b and Henryk K o z | o w s k i b

aDepartment of Chemistry, University of Siena, Via Aldo Moro, 53100 Siena, Italy bFaculty of Chemistry, University of Wroctaw, Joliot-Curie 14, 50-383 Wroctaw, Poland

Lincomycin, a clinically important natural antibiotic synthesized by Streptomyces lincolnensis, is particularly active against Gram-positive bacteria and it is widely used in human and veterinary applications.

The structural similarity to aminoglicoside antibiotics and the occurrence of a peptide linkage make lincomycin a potentially strong ligand for copper(II). It has been recently shown that copper binds lincomycin strongly and the most stable complex in water solution at pH L~ 7.0 was suggested to be a CuH_2L species.

The copper(II) complex of lincomycin in water solution at pH = 7.15 was characterized by ~H- and ~3C-NMR and UV-Vis spectroscopy. A 1:1 complex is formed in these conditions. The temperature dependence of spin-lattice relaxation rates was measured, showing that all protons behave in a similar fashion and slow exchange conditions prevail. The spin-lattice relaxation rate enhancements were interpreted by the Solomon-Bloembergen-Morgan theory. Reorientational dynamics of the complex was approximated by evaluating the motional correlation time of free lincomycin in water solution. The observed proton and carbon relaxation rate enhancements allowed to calculate copper- proton and copper-carbon distances, that were used for building a molecular model of the complex. The obtained data provides an interpretation of the relatively high stability constant.

1. Pechere J.C., Pathol.Biol., 34, 119-122 (1986). 2. Jezowska-Bojczuk M., Lesniak W., Szczepanik W., Gatner K., Jezierski A., Smoluch M. and Bal W.,

J.Inorg.Biochem., in press (2001).

3. Gaggelli E., Gaggelli N., Valensin D., Valensin G., Jezowska-Bojczuk M. and Kozlowski H., Inorg.Chem., submitted.

Human cytosolic iron regulatory protein 1 contains a linear iron-sulfur cluster

Jfirgen Gailer, a Graham N. George, b Ingrid J. Picketing, b F. Ann Walker c and Joy J. Winzerling a

Department of Nutritional Sciences, The University of Arizona, Tucson, AZ, 85721, USA, (e-mail: j_gailer@hotmail.eom.) b Stanford Synchrotron Radiation Laboratory, Stanford Linear Accelerator Center, MS 69, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA. c Department of Chemistry, The University of Arizona, Tucson, AZ, 85721, USA.

Iron Regulatory Protein 1 (IRP1) is found in all higher forms of life and regulates cellular iron uptake and storage by reciprocal translational control of the synthesis of transferrin receptors and ferritin. We purified recombinant human IRP1 (N-terminal His-tag) from E. Coli lysate by immobilized metal affinity chromatography and anion-exchange chromatography. After reconstitution of the iron-sulfur cluster and size-exclusion chromatography, the iron-sulfur cluster was spectroscopically characterized by X-ray absorption spectroscopy and electron paramagnetic resonance (EPR) spectroscopy. The Fe near edge spectra suggested an all ferric cluster and Fe EXAFS spectra revealed 4 Fe-S at 2.25 A, 1 1/3 FeFe at 2.69 A and a small long distance feature at 5.4 A. Modeling the EXAFS using a full multiple scattering treatment assuming a linear (RS)zFeS2FeS2Fe(SR)z core constructed using the bond-lengths form the single scattering EXAFS analysis, and assuming a cluster with D: symmetry resulted in an excellent fit to the experimental data. Thus, the EXAFS data indicate the presence of a linear iron-sulfur cluster. The EPR spectrum of recombinant human IRP1 showed a small peak at g-9.4, an isotropic feature at 4.3, and a sharper axial signal near g-2.03. The g-9.4 and 4.3 features are characteristic of an S=5/2 system in a rhombic environment and are very similar to those values reported for the linear [3Fe-4 S] cluster of mitochondrial aconitase,1 and to the model compound of Hagen et al. z In summary, we have shown that reconstituted IRP1 contains a linear species, which is likely to be Cysz[FeS~FeS2 Fe]Cysz. It remains to be seen whether this linear cluster occurs in vivo.

1. Kennedy M.C.; Kent T.A.; Emptage M.; Merkle H.; Beinert H.; Miinck E., J. Biol. Chem.259, 14463-14471 (1984). 2. Richards A.J.M; ThomsonA.J.; Holm R.H.; Hagen K.S., Spectrochim Acta 46A, 987-993 (1990).

Journal of lnorganic Biochemistry 86 (2001) 227

Intramolecular ligand exchange reaction of (SP-4-2)-dichlorobis(2- hydroxyethylamine)platinum(II) and its tetrachloroplatinum(IV) counterpart

Markus Galanski a, Wolfgang Zimmermann a, Christian Baumgartner a and Bernhard K. Keppler a

C, institute of Inorganic Chemistry, University of Vienna, Waehringer Str. 42, A-1090 Vienna, Austria, (e-mail. galanski@ap.univie.ac.at)

The chemistry of the bis(ethanolamine) complexes (SP-4-2)-dichlorobis(2-hydroxy-ethylamme)platinum(II) and (OC- 6-22)-tetrachlorobis(2-hydroxyethylamine)platinum(IV) in aqueous solution has been invest1 platinum(II) compound forms very stable monoadducts with 5'-GMP. In water the platinum based complexes are converted into (SP-4-3)-chloro(2-hydroxyethylamine)(2- ethanolatoamine-KZN, O)-platinum(II) and (OC-6-31)-trichloro(2-hydroxyethylamine)(2- ethanolatoamine-K2N, O)-platinum(IV) with a chelating ethanolatoamine ligand by intramolecular ligand exchange reaction which was proven by ~H and 2D-~SN,~H-HMQC NMR experiments and crystal structure determination.

These results clearly indicate that the formation of monoadducts of the before mentioned dichloroplatinum(II) complex with 5'-GMP which are very stable over a period of more than 10 days can be explained by the presence of the ethanolatoamine chelate in solution ~.

1. Galanski M., Zimmermann W., Baumgartner Ch. and Keppler B.K., Eur. J. Inorg. Chem., 1145-1149 (2001)

We gratefully acknowledge the FWF (Austrian Science Fund) for financing the project (Project Number: P 12299).

ated due to the fact that the

HO I

H2C~ CH2 I

H2N ~ ~CI

Pt / \ H2N O

\ / H2C CH 2

Reaction of (SP-4-2)-dichlorobis(2-hydroxyethylamine)platinum(II) with 5'-GMP, a CZE-ESI-MS Study

Markus Galanski a , Angelika Kting a, Christian Baumgartner a and Bernhard K. Keppler a

Institute of Inorganic Chemistry, University of Vienna, Waehringer Str. 42, A-1090 Vienna, Austria, (e-mail. galanski@ap.univie.ac.at)

The binding behaviour of the tumour inhibiting complex (SP-4-2)-dichlorobis(2-hydroxyethylamine)platinum(II) to the nucleotide 5'-GMP has been studied by capillary zone electrophoresis (CZE)1.Time dependent coordination of 5'-GMP to the platinum(II) centre was investigated using diode array UV detection. The binding has shown to be dependent on NaC1 concentration as well as on pH value. For elucidation of the reaction pathway coupling of CZE to a mass spectrometer via an electrospray interface was applied. Contrary to common platinum complexes used in cancer therapy, the complex investigated forms a very stable monoadduct via intramolecular ligand exchange reaction.

CZE-ESI-MS has shown to be a powerful method for the direct analysis of adducts formed during reaction of nucleotides with platinum based compounds. Selected ion monitoring represents a selective, sensitive and robust method for this kind of investigation. Platinum-5'-GMP-adducts as well as the parent nucleotide could be baseline separated and analysed online by CZE-ESI-MS coupling within less than 10 minutes.

HO

I H2C~cH 2

I N,N\ /N,-GMP Pt / \ H2N ~ /0

H2C CH 2

1. Zenker A., Galanski M., Bereuter T.L., Keppler B.K. and Lindner W., J. Biol. Inorg. Chem. 5,498-504 (2000)

We gratefully acknowledge the FWF (Austrian Science Fund) for f'mancing the project (Project Number: P14290).

228 Journal of Inorganic Biochemistry 86 (2001)

Thermal and photochemical interaction of dioxygen with binuclear copper(I) complexes containing bis[2-(2-pyridyl)ethyl]amine chelators

Benedikt Galliker a, Susan Kaderli a, Kenneth D. Karlin b, Hong-Chang Liang b, Christiana Xin Zhang b, and Andreas D. Zuberbiihler ~

Institute of Inorganic Chemistry, University o f Basel, Spitalstrasse 51, 4056 Basel, S WITZERLA ND

(e-mail. Beni. Galliker@stud. unibas, ch) a Department of Chemistry, The Johns Hopkins University, Baltimore, MD 21218, USA

Kinetic and thermodynamic parameters of dioxygen interaction with dicopper(I) complexes of ligands L 1-3 are discussed

and compared to results obtained with ligands containing identical bis[2-(2-pyridyl)ethyl]-amine chelators but an aromatic spacer in place of the more flexible saturated 5-membered chains. Basically, all systems can be described by a relatively simple mechanistic scheme:

Cu~ L 2÷ + O 2 ~ C u 2 L (02) 2+ (+1)

Cu2L(O2) 2÷ ::~ decomposi t ion products (2) In all cases, the formation reaction (+1) is described by low or even negative activation enthalpies (-11 to +17 kJ/mol)

and strongly unfavorable activation entropies. Complexes with ligands 2 and 3 containing coordinating oxa or N-Bz groups are up to 100-fold less reactive than those with 1 most likely due to interaction of X with the metal ion (k+~ (183 K): 1:4.1t03 Mdsl; 2:3.5t01 Mlsq; 3 : 1 0 M-Isl). Back reactions (-1) have much higher activation enthalpies around 70 to 85 kJ/mol, combined with positive entropies. The influence of the group X is also directly reflected in the thermodynamic stability of the peroxo complexes Cu2L(O2) 2+: the higher the coordinating power of X, the lower the equilibrium constant Kl = k+~/k_b in contrast with expected direct electronic effects. Transformation of the pseudoreversible side-on peroxo complexes into irreversible oxidation products is strongly photosensitized, most prominently so with the aromatic spacer.

Supramolecular structures of metronidazole and its copper(II), cobalt(II) and zinc(II) coordination compounds

Nadeshda Galv~n-Tejada a, Norfih Barba-Behrens a, Sylvain Bemrs b ~Department of Chemistry, National University o f Mexico, C.U. Av. Universidad 3000, Coyoacan,

04510, Mexico D.F., MEXICO (e-mail." norah@servidor, unam.mx) bB. Universidad Autrnoma de Puebla, Pue., Mdxico.

The binding of metal ions may control the association and conformation of biologically active molecules and so affect their chemical and biological properties. We have investigated the coordination behaviour of biological active imidazole derivatives I, and in nitroimidazoles, the nitro group may act as a coordination site 2. In this work we present the synthesis and characterization of Cu(II), Co(II) and Zn(II) compounds with the antibiotic metronidazole (emni),l(~- hydroxyethyl)-2-methyl-5-nitroimidazol). Intra- and inter-molecular associations gave place to supramolecular structures. Helicoidal chains with [Zn(emni)2X2] (X TM C1, Br) and [Cu(emni)ffOAc)2]2 were obtained, as for [Co(emni)2X2] and [Cu(enmi)2C12]2. bidimensional sheets were formed.

1). Castillo-Blum S.E.; Barba-Behrens N., Coord. Chem.Rev., 196, 3 (2000); 2). Barba-Behrens N., Mutio-Rico A.M., Joseph-Nathan P., Contreras R. Polyhedron,10, 1333 (1991).

[Co(emni)2CI2].

DGAPA-UNAM is acknowledge for fmancial support

Journal of Inorganic Biochemistry 86 (2001) 229

Selective macrocyclic copper complexes as catalysts for the polymerization of 2,6-dimethylphenol

P a t r i ck G a m e z , R o s i e n n e S t e e n s m a , W i l l e m L. D r i e s s e n , J an Reed i jk .

Leiden Ins t i tu te o f Chemis try , Univers i ty o f Leiden, P.O. Box 9502, 2300 RA, Leiden, The Ne ther lands (e-mail." p . g a m e z @ e h e m . l e i d e n u n i v . n l )

The copper-catalyzed polymerization of 2,6-dimethylphenol is an important industrial process, which leads to poly- phenylenether (PPE), a valuable material, and to the undesirable diphenylquinone (DPQ). According to mechanistic studies, PPE formation is due to dinuclear species, while DPQ is due to mononuclear ones. The catalytic activities of macrocyclic dinuclear copper complexes, leading to high selectivities in PPE, strongly support the proposed mechanism.

1. Reedijk J, Bouwman E. (Eds), Bioinorganic Catalysis, 2 ~a Edition, Marcel Dekker, Inc., New York, 1999.

2. Hay, A.S., J. Polym. Sci. A. 36, 505 (1998). 3. Gamez, P., Simons, C., Driessen, W.L., Challa, G., Reedijk, J., App. Catal. A., 214

(2001) 187-192. 4. Gamez, P., Simons, C., Steensma, R., Driessen, W. L., Challa, G., Reedijk, J., Eur.

Polym. J., 37 (2001) 1293-1296.

I

Support from the Dutch National Research School Combination Catalysis (HRSMC and NIOK) is gratefully acknowledged.

Insight into the electronic structure of a low spin {FeNO} 6'7'8 system

Ricardo Garcia, Eckhard Bill, Eberhardt Bothe, Thomas Weyhermtiller, Karl Wieghardt Max Planck lns t i tu t f i ir S t rah lenchemie , St i f ts traf le 34 - 36, 45470 Mfilheim an der Ruhr,

G E R M A N Y (e-mai l . g a r c i a @ m p i - m u e l h e i m . m p g . d e )

A pendent arm N-derivatized cyclam provides a pentadentate redox-innocent ligand, which, due to its trans conformation around the iron, forces it to adopt a low spin state. The {FeNO} 7 complex (picture) was prepared as a PF6 salt, then oxidized and reduced to the corresponding {FeNO} 6 and {FeNO} 8 systems. The three complexes were characterized by UV, IR, EPR and Mrl3bauer spectroscopies. The {FeNO} 7 shows a S=1/2 ground state which is attributed to Fe HI intermediate spin (S=3/2) coupled to NO-. Upon le- abstraction, the isomer shift in the M613bauer indicates that the iron center is oxidized to Fe TM. At the same time, the nitrosyl ligand displays a NO v,s vibration which is shifted about 290 cm -~ towards higher energies. Upon l e addition, the NO V~s band is shifted about 340 cm q towards lower energies, and the MrBbauer parameters are the same as that of the {FeNO} 7 complex, indicating that the iron center is hardly affected by reduction.

1. Hauser, C.; Glaser, T.; Bill, E.; Weyhermtiller, T; Wieghardt, K. ; J. Am. Chem. Soc. 122(18); 4352-4365 (2000). 2. Grapperhaus, C.A.; Mienert, B.; Bill, E.; Weyhermtiller, T.; Wieghardt, K. ; Inorg. Chem. 39(23); 5306-5317 (2000).

230 Journal of Inorganic Biochemistry 86 (2001)

Interactions of Ru(II) polypyridyl enantiomers with the oligonucleotides d(GTCGAC)2 and d(CGCGAATTCGCG)2

A. Garouf is , G. Malandr inos , A. Myar i , M. M y l o n a s and N. Hadjil iadis.

Laboratory of Inorganic and General Chemistry, Department of Chemistry, University of Ioannina, Ioannina 45110, GREECE (e-mail: agaroufi@ce.uoi.gr).

The interactions of A- and A-[(bpy)zRu(HPIP)] Clz (HPIP=2-(2-hydroxyl-phenyl)imidazo [4,5,-f] [ 1,10]phenanthroline) with the self complementary hexanucleotide d(GTCGAC)z, were studied using multidimensional NMR spectroscopic techniques and Electrospray-MS. The results show that the A- isomer binds tightly to the oligonucleotide by partial intercalation between the base pairs, while the A- one, binds weakly suggesting a groove-type binding.

Additionally, the binding properties of the enantiomers A- and A-[(bpy)zRu(PBIM)]CI2 and A- and A- [(bpy)zRu(PQX)]CI2 ( PBIM = 2-(2'-pyridyl) benzimidazole and PQX = 2-(2'-pyridyl)quinoxaline ) with the dodeca- nucleotide d(CGCGAATTCGCG)2 were studied, in an attempt to determine how the "planar" length of the aromatic ligands ( PBIM < PQX < HPIP ) can be correlated to the way that the complex approaches the oligonucleotide duplex. Finally, the interactions of the enantiomers A- and A- [(bpy)2Ru(bpyGHL)]C12 (bpyGHL = 4'- (Gly-His-Lys)-2,2'-bipyridine) with the same dodecamer were studied, and preliminary results will also be presented.

"planar" length

HPIP PQX BZIM

Financial support from the Greek G.S.R.T. (program 99ED/123) is gratefully acknowledged

Hydroxamic acids, their metal complexes and biological applications

Declan Gaynor a, Zoya A. Starikova b, Wolfgang Haase c, Kevin B. Nolan a aRoyal College of Surgeons in Ireland, 123 St. Stepthen's Green, Dublin 2, Ireland. (email. kbnolan@rcsi, ie) bX-Ray Structure Centre, General and Technical Chemistry Division, Academy of Sciences of Russia, Vavilov Str. 28, Moscow B-334, 117813, Russia. CTechnische Universitiit Darmstadt, lnstitute fiir Physicalische Chemie, Petersenstr. 20, D- 64287, Darmstadt, Germany.

Hydroxamic acids play a variety of roles in biology and medicine, many of which are due to the chelating ability of the hydroxamate group. We are investigating hydroxamic acid derivatives as aspirin analogues and have also shown that they are effective NO donors t. The complexing nature of the hydroxamate group may be influenced by other coordinating groups in the molecule, giving structurally diverse complexes. We report that whilst 3- aminophenylhydroxamic acid, 3-AphaH, reacts with CuSOa.5H20 to give the novel helical polymer [Cu3(3- Apha)4(HzO)SO4]~.8H20 containing interlinked repeating units with magnetically independent copper(II) sites, 2-AphaH gives {Cu[Cu(2-AphaH.0]a(g-SO4)t(H20)2}2.10H20, a novel dimeric, antiferromagnetically coupled 'metallacrown' and 4-AphaH gives the monomeric complex Cu(4-Apha)2.H202. Acetylation of 2-AphaH resulted in formation of a cyclic hydroxamic acid, complexes of which we have also studied.

1. C.J. Marmion, T. Murphy, J. R. Dockerty, K. B. Nolan. J. Chem. Soc. Chem. Commun., 2000, 1153. 2. D. Gaynor, Z. A. Starikova, W. Haase, K. B. Nolan, J. Chem. Soc. Dalton Trans., 2001, 1578.

We acknowledge the financial support of RCSI, Enterprise Ireland, COST-D8 and SBIC.