12.158 lecture 7 - mit opencourseware12.158 lecture 7 • sterols part 2 – sterol biosynthesis...
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12.158 Lecture 7
• Sterols part 2 – Sterol biosynthesis review and revision – Steroids as age and environment
indicators – Enigmatic steroids 2- and 3-alkyl and
carboxysteroids
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Sterols, Eukaryotes and O2squaleneepoxidesqualeneepoxide 29292929squalenesqualene1.14.99.7 + O21.14.99.7 + O2 28282828
OO
2222222221212121 2626262624242424
25252525
LANOSTEROL BRANCHLANOSTEROL BRANCH 5.4.99.7 5.4.99.85.4.99.7 5.4.99.8 CYCLOARTENOL BRANCH 1212
CYCLOARTENOL BRANCH1212
18 20 2318 201818 2320 2320 23
17171717 2727272711111111 1313131319191919 D 16DDD 161616CCCC1111 9999141414142222
8 15888 151515PROTOSTEROLSPROTOSTEROLS 10101010BBBBAAAA
77773 5333 555H OH O HOHO
lanosterollanosterol cycloartenol 4 64 6cycloartenol 4 64 6
2.1.1.41 1.14.13.70+ 3 O22.1.1.41 1.14.13.70+ 3 O2 smt1smt1
24-methylenecycloartenol24-methylenecycloartenol
smo1 + 3 O2 , 1.1.1.170, 1.1.1.270smo1 + 3 O2 , 1.1.1.170, 1.1.1.270eburicoleburicol4,4-dimethyl-5?-cholesta-8,14,24-trien-3?-ol4,4-dimethyl-5?-cholesta-8,14,24-trien-3?-ol H OH OHOHO HOHO
1.14.13.70+ 3 O21.14.13.70+ 3 O2 1.3.1.701.3.1.70 cycloeucalenolcycloeucalenol
4,4-dimethyl-5?-ergosta-8,14,24(28)-trien-3?-ol4,4-dimethyl-5?-ergosta-8,14,24(28)-trien-3?-ol 5.5.1.95.5.1.94,4-dimethyl-5?-cholesta-8,24-dien-3?-ol4,4-dimethyl-5?-cholesta-8,24-dien-3?-ol
HOHO HOHO HOHO
1.14.13.72, 1.1.1.170, 1.1.1.270 +3 O21.14.13.72, 1.1.1.170, 1.1.1.270 +3 O2 obtusifoliolobtusifoliol1.3.1.701.3.1.70
1.14.13.70+ 3 O21.14.13.70+ 3 O24,4-4,4 dimethylfecosterol-dimethylfecosterol 4?-methyl zymosterol4?-methyl zymosterolH OH O H OH O
HOHO
1.14.13.72, 1.1.1.170, 1.1.1.270 +3 O21.14.13.72, 1.1.1.170, 1.1.1.270 +3 O2 1.14.13.72, 1.1.1..170, 1.1.1.270 +3 O21.14.13.72, 1.1.1..170, 1.1.1.270 +3 O2 4?-methyl-5?-ergosta-8,14,24(28)-trien-3?-ol4?-methyl-5?-ergosta-8,14,24(28)-trien-3?-ol
4?-methylfecosterol4?-methylfecosterol 1.3.1.701.3.1.70zymosterolzymosterol
H OH OHOHO H OH O
1.14.13.72, 1.1.1..170, 1.1.1.270 +3 O21.14.13.72, 1.1.1..170, 1.1.1.270 +3 O2 5.3.3.55.3.3.5 4?-methylfecosterol4?-methylfecosterol
5.3.3.55.3.3.5fecosterolfecosterol 5?-cholesta-7,24-dien-3?-ol5?-cholesta-7,24-dien-3?-ol
HOHO H OH OHOHO
erg2erg2 1.3.1.721.3.1.72 24-24 methylenelophenol-methylenelophenol
episterolepisterol smt2smt2HOHO lathosterollathosterol HOHO H OH O
erg3+ Oerg3+ 2O2 1.3.3.2 + O21.3.3.2 + O2 24-ethylenelophenol24-ethylenelophenol
5,7,24(28)-5,7,24(28)ergostatrienol-ergostatrienol smo2 + 3 O2 , 1.1.1.170, 1.1.1.270smo2 + 3 O2 , 1.1.1.170, 1.1.1.270 H OH O 7-dehydro-cholesterol7-dehydro-cholesterol HOHO
HOHO
1.3.1.211.3.1.21erg5 + Oerg5 + 2O2 24-ethylenelathosterol24-ethylenelathosterol
5,7,22,24(28)-5,7,22,24(28)ergostatetraenol-ergostatetraenol 1.3.3.2 + O1.3.3.2 + 2O2HOHO cholesterolcholesterol HOHO
HOHO
1.3.1.711.3.1.71 24-methylene 5-dehydroepisterol24-methylene 5-dehydroepisterol
1.3.1.211.3.1.21ergosterolergosterolHOHO
HOHO
isofucosterolisofucosterol
dwf1dwf1H OH O
sitosterolsitosterol12 O2 11 O2 11 O2 H OH O
Burial & diagenesis ergostane cholestane sitosterane
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The effect of oxygen on biochemical networks and the evolution of complex life.
Jason Raymond and Daniel Segre' Science 311, 1764-1767 (2006)
Cholesterol
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squalene hopene,tetrahymanol
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http://prelude.bu.edu/O2/networks.html
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Oxidosqualene Cyclase
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Symbiogenesis:the phylogenetic
tapestry ofeukaryotes
http://www.life.umd.edu/ This image has been removed due labs/delwiche/ to copyright restrictions.
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Eukaryote Diversity & Chloroplast Endosymbiosis
Anaerobes stem of tree?
Algae Forams
Radiolaria
This image has been removed due to copyright restrictions.
©Jacob Waldbauer, 2007 Keeling et al. 2005
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Phytosterols Whereas vertebrates and fungi synthesize sterols from epoxysqualene through the lanosterol, plants cyclize epoxysqualene to cycloartenol as the initial sterol. Q. Presumably lanosterol biosynthesis predates cycloartenol biosynthesis? What might have driven the lanosterol-cycloartenol bifurcation?
HO cycloartenol
HO β-sitosterol 24-ethyl-5-en-3β-ol HO
stigmasterol 24-ethyl-5,22-dien-3β-ol
HO ergosterol 24-methyl-5,7,22-trien-3β-ol
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Phytosterols C30 sterols are generally minor components of organisms and immature sediments. However, when they occur, they have distinctive structures that are easily recognised in the ancient record.
red algal spongeHO sterol HO sterol
HOHO dinosterol 4a-methyl-24-ethyl
cholestan-3β-ol
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Oxidosqualene Cyclase Alignment
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Microorganism Microalgae Bacillariophyceae Bangiophyceae Chlorophyceae Chrysophyceae Cryptophyceae Dinophyceae Euglenophyceae Eustigmatophyceae Haptophyceae Pelagophyceae Prasinophyceae Raphidophyceae Rhodophyceae Xanthophyceae Cyanobacteria: Methylotrophic bacteria Other bacteria Yeasts and fungi Thraustochytrids
Major or common sterols
C28D5,22, C28D5,24(28), C27D5, C29D5, C27D5,22 C27D5, C27D5,22, C28D7,22 C28D5, C28D5,7,22, C28D7,22 C29D5,22, C29D5 C29D5,22, C29D5, C28D5,22 C28D5,22 4Me-D0, dinosterol, C27D5, C28D5,24(28) C28D5,7,22, C29D5, C28D7, C29D5,7, C28D7,22 C27D5 (marine) or C29D5 (freshwater) C28D5,22, C27D5, C29D5,22, C29D5 C30 D5,24(28), C29D5,22, C29D5, C28D5,24(28) C28D5, C28D5,24(28), C28D5 C29D5, C28D5,24(28) C27D5, C27D5,22 C29D5, C27D5 C27D5, C29D5, C27D0, C29D0 (evidence equivocal) 4Me-D8 C27D5 C28D5,7,22, C28D7, C28D7,24(28) C27D5, C29D5,22, C28D5,22, C29D5,7,22
The nomenclature is CxDy where x is the total number of carbon atoms and y indicates the positions of the double bonds. In general, C28 sterols have a methyl group at C-24, and C29 sterols have a 24-ethyl substituent. Table adapted from data in Volkman (1986); Jones et al. (1994) and Volkman et al.
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Uncommon Marine Sterols
HO HO 24-methyl-27-nor sterols and stanol 24-nor sterols known in sponges: C27 compounds a range of algae & invertbrates: C26
H H19-nor sterols A-nor sterolsR=H, CH3, C2H5, methylene spongesΔ22 trans unsaturationprobably formed by de-alkylationof algal sterols
HO
H
H
R
HOH2C
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Uncommon Marine Sterols (2)
HO HO
Aplysterol Gorgosterol
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How to identify sterols by GC-MS of TMS and acetate derivatives
• Relative Retention Times of Nematode Sterols
• Mass Spectra of Nematode Sterols
• Mass Spectral Data for Nematode Sterols, Analyzed as Steryl AcetateDerivativesa Steryl acetate________Mass spectrum (m/z, relative intensity tobase peak)__Cholesta-5,7,9(11)-trienol 424 (5), 364 (100), 349 (33),251 (31), 209 (64), 197 (43), 195 (52)Cholest-8(14)-enol 428 (100),413 (18), 368 (6), 353 (13), 315 (16), 288 (7), 273 (6), 255 (21), 229(42), 213 (43), 81 (80), 55 (83)Cholesterol 368 (100), 353 (14), 260(15), 255 (13), 247 (18), 213 (14), 147 (48), 145 (37), 81 (74), 55(71) Cholestanol430 (12), 415 (2), 370 (33), 355 (16), 316 (3), 276(28), 275 (18), 257 (4), 230 (17), 215 (100), 201 (18), 147 (32), 81(53)
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Sterol Reading #1
Text has been removed due to copyright restrictions.
Please see http://www.springerlink.com/content/q05172k241v60328
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Reconstruction of past biota
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Biomarkers and Fossils what can they can say:
Who are the major groups of marine primary producers today?
Which groups dominated at different periods in the geologic past?
How is plankton growth recorded in rocks – and oil?
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What factors influence the completeness of the fossil record of marine plankton?
How has long-term ecological succession of marine plankton affected the evolution of other organisms and biogeochemical cycles?
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Marine Primary Producers
Today, 2 major groups:
Acquired photosynthesis by secondary endosymbiosis
Were preceded by red/green algae & prokaryotic phototrophs
Left a rich body & molecular fossil recordRose to ecological prominence relatively
recently
Picocyanobacteria Prochlorococcus/
Marine Synechococcus
These images have been removed due to copyright restrictions.
Chl a+c Phytoplankton Diatoms
Dinoflagellates Coccolithophorids
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Eukaryote Diversity & Chloroplast Endosymbiosis
Anaerobes stem of tree?
Algae Forams
Radiolaria
This image has been removed due to copyright restrictions.
©Jacob Waldbauer, 2007 Keeling et al. 2005
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The Fossil Record of Phytoplankton - one form of bias: where sediment is deposited
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Another form of Bias:Age of the Ocean Floor
200 0 NOAA NGDC
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White Cliffs of Dover
Rocks Made of Plankton Cretaceous coccoliths
Diatomaceous Earth Mine, Wallace Co., Kansas Grace Muilenburg, Kansas Geol. Surv.
K~T Boundary at Stevns Klint Denmark
Courtesy of Organic Geochemistry Group, Universitat Bremen. Used with permission.22
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Succession in the Photosynthetic Plankton of the Ocean: A Perspective Drawn from
Chemical Fossils
Roger E. Summons & Jacob R. Waldbauer (MIT)Andrew H. Knoll (Harvard University)
John E. Zumberge (GeoMark Research)
Successions in Biological Primary Productivity in the Oceans. In Falkwoski P. and Knoll A.H. (eds) The Evolution of Photosynthetic Organisms in the Oceans, 2006.
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Evolutionary Trends from Rocks & Oils: Present-day sample localities
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Evolutionary Trends from Rocks & Oils• Sedimentary organic matter is the direct geologic legacy of
primary production • Massive accumulations of organic matter in petroleum systems
worldwide record ocean biogeochemistry • Oils are widely available, accessible, abundant & carry the same
kind of evolutionary information that is buried in sediments • Oils reflect the natural ‘average’ in the variation in source rock
organofacies • GeoMark Database: Biomarker parameters from over 1800
microbial-sourced oils (no terrigenous input) have been averaged to obtain 133 petroleum systems from the Neoproterozoic to Miocene
• The source rock type and age for many of the oils in GeoMark’s database are known based on extensive integration of geological and geochemical frameworks
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0.6
PaleoLatitude vs Carbonate-Sourced OilsC
29/C
30H
1.4
1.2
1.0
0.8
carbonate marl shale
0.4
0.2 -80 -60 -40 -20 0
Paleo Latitude 20 40 60 80
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Pentacyclic Terpane Ratios C
31R
/H
0.60
0.55
0.50
0.45
0.40
0.35
0.30
0.15
0.20
0.25 carbonate marl shale lacustrine
0.10 0.2 0.4 0.6 0.8
C29/H 1.0 1.2 1.4
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• Clearly, these groups rise to paleontological prominence in Mesozoic and Cenozoic oceans, but…
• Is there an earlier, “cryptic” evolutionary history? – Unmineralized or poorly mineralized stem diatoms or
coccolithophorids? – Non-diagnostic fossils of dinos (sans archeopyle) among
older acritarchs?? – Help from molecular clocks?? – Sedimentary record:Biomarker molecules are most
informative
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C28/C29 Sterane Ratios: The Rise of Modern Plankton
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Dinoflagellate Biomarkers-Petroleum Record
C25
C16
C15
C17 C12
C21 C22
C2
C1
C4
C3
C5
C8
C9
C6
C7
C18
C19 C20
C10
C14
M8
M1
M10
M6
M4
M9
M3 M2
M7
M5
DS67
DS12 DS38
DS3
DS26DS8
DS11
DS52
DS49
DS27
DS10
DS16
DS57
DS69 DS62
DS24
DS60 DS55
DS14
DS68
DS50
DS13
DS61
DS1
DS20
DS19
DS65 DS17
DS46
DS42
DS2
DS6
DS43
DS71
DS41
DS59
DS56
DS34
DS70
DS73DS64 DS63
DS9
DS4
DS66
DS47
DS53
DS37
DS39
DS15 DS40
DS44
DS48
DS72
DS51
DS45
DS74
DS21
DS5
DS54
L23
L12
L17
L11
L7
L5
L21
L1
L20
L18
L6
L16
L8
L15
L4
L3
L13
L14
L19
L2
L9
L24
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 50 100 150 200 250 300 350 400 450 500 550 600
Source Rock Age (mybp)
Aro
mat
ic D
inos
tera
nes
(3/3
+6)
carbonate marl distal shale lacustrine End Cretaceous End Permian End Proterozoic
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Aro
mat
ic d
inos
tero
ids/
2+3-
met
hyls
Distribution of dinosteroids in Phanerozoic
sediments This image has been removed due to copyright restrictions. Moldowan and Talyzina
Science 281,168-1170, 1998
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C26 steranes
21-nor Unknown source
24-nor Unknown source
27-nor Unknown source
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Secular Change in C26 Sterane AbundanceApplication of 24-norcholestanes for constraining source age of petroleum
A. G. HOLBA et al. Org. Geochem. 29,1269 -1283, 1998 Rampen et al., AGU 2004:�����..Another specific biomarker is 24-norsterol. Its value as an age diagnostic biomarker was already reported (3), but the source of this sterol was still unknown although a diatomaceous source was assumed. We have now found this sterol in the diatom species Thalassiosira aff. Antarctica. In combination with the knowledge that the 24-norsterol production increased substantially during the Cretaceous this may provide a tool to predict the mutation rate of the Thalassiosirales. Our data show that molecular paleontology can assist in obtaining more reliable estimates of the molecular clock rate and thus be an important tool
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Diatom sterol Diatom sterane
in reconstructing the evolution of diatoms.
HO 24-nor
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C26 steranes elution pattern
This image has been removed due to copyright restrictions.
Moldowan et al GCA 55, 1065, 1991
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Secular Change in C26 Sterane Abundance Application of 24-norcholestanes for constraining source age of petroleum
A. G. HOLBA et al. Org. Geochem. Vol. 29, pp. 1269 -1283, 1998
Courtesy Elsevier, Inc., http://www.sciencedirect.com. Used with permission. 35
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Diatom-specific HBI & their Geologic Occurrence Highly branched acyclic isoprenoid alkenes and alkanes
The Rise of the Rhizosolenid Diatoms Jaap S. Sinninghe Damsté, Gerard Muyzer, Ben Abbas, Sebastiaan W. Rampen, Guillaume Massé, W. Guy Allard, Simon T. Belt, Jean-Michel Robert, Steven J. Rowland, J. Michael Moldowan, Silvana M. Barbanti, Frederick J. Fago, Peter Denisevich, Jeremy Dahl, Luiz A. F. Trindade and Stefan Schouten
23 APRIL 2004 VOL 304 SCIENCE
C20 HBI C25 HBI
•Identified in the diatom genera
This image has been removed due to copyright restrictions.
Rhizosolenia, Haslea, Navicula, and Pleurosigma only •Biological products have 1-6 unsaturations; fossils fully saturated
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C30 Desmethylsteranes
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C30 Desmethyl Steranes Oil from Southern Oman
OM20 24-i-propylcholestanes 414 217
NZ Kora 24-n-propylcholestanes 414 217
59:00 1:00:00 1:01:00 1:02:00 1:03:00 1:04:00 Time
ααα 20R
ααα 20S
αββ 20R+S
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C30 Desmethyl Steranes Eastern Siberia Oils
59:00 1:00:00 1:01:00 1:02:00 1:03:00 1:04:00 Time
ES36 414 217
ES89 414 217
i / n > 1
i / n < 1
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Stratigraphic column of Huqf Supergroup withrepresentativ e lithology, biostratigraphy and geochronologica This image has been removed
l constraints. due to copyright restrictions.
GD Love et al. Nature 457, 718-721 (2009) doi:10.1038/nature07673
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Catalytic hydropyrolysis (HyPy) biomarker geochemistry applications
� Pyrolysis assisted by high H2 pressure (15 MPa) and a molybdenum catalyst (active phase is MoS2)
� A powerful tool for releasing bound biomarkers
� high yields of biomarker hydrocarbons
� less structural/stereochemical alteration
� Love et al. (1995) Org. Geochem. 23, 981
� info on bonding (D2)
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Temperature-programmed, open-system pyrolysis (fast residence time of volatile
Hydropyrolysis apparatus
High pressurehydrogen
Thermocouple
Reactor tube
Sample bed with dispersed Mo catalystElectrical
connectors
Gas collection And measurement
Mass-flow controller
Pressure transducer
Cold trap
Temp prog. amb. – 500oC @ 8oC/min H 2 pressure15 MPa sweep gas flow10 dm3/min
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Comparison of free and kerogen-bound hydrocarbons TICs of saturates for a Minassa-1(A1C) sample
05 May 17 10 17 19 std.100 * Free saturated hydrocarbons 15 Ph 21 23 * = std.
% 25 hopane/sterane regioni18Pr 27
x x 29 31xx x x x x
2 05 May 31 08
17 19 HyPy of Kerogen
100
15 21 23
% Ph 25 hopane/sterane region
i18 27Pr x x x x x 29 31 x x x x 2 Time
15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.00 55.00 60.00 65.00 70.00 75.00 80.00 85.00 90.00
Numbers refer to carbon chain lengths of n-alkanes X= series of mid-chain methylalkanes (unknown origin)
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MRMGC-MS ion chromatograms of C26–C30 desmethylsteranes
released from catalytic hydropyrolysis of a Masirah Bay Formation (JF-1) and a Ghadir
Manquil Formation (GM-1) kerogen.
This image has been removed due to copyright restrictions.
GD Love et al. Nature 457, 718-721 (2009) doi:10.1038/nature07673
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21418 b/c +std 50ng/1000ul 2- & 3-methylsteranes 03100216 100 6
60.82 2.11 414.423 > 231.212
62.82 4-methylsteranes
% 58.6459.04 63.06 58.15
65.12 65.63
0 03100216 100 62.80 414.423 > 217.19661.32
57.57 58.62%
59.81 63.00s
52.24 53.10 55.95 56.86 64.23
o0
03100216 100 61.20 400.407 > 217.196
59.91 56.11
% 57.12 58.76
55.39
0 03100216 100 61.14 404.432 > 221.221
%
51.57 55.02 58.23 64.050 Time
MRM –GCMS howing C30 steranes f a marine sediment
52.50 55.00 57.50 60.00 62.50 65.00 67.50 70.00
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2- & 3alkylsteranes
Note the exact co-elution of the
four synthetic isomers with the
equivalent peaks of the
Phosphoria oil
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2- & 3alkylsteranes
Note the different isomer
This image has been removed due to copyright restrictions. preference for
marine vs lacustrine sediments
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MIT OpenCourseWarehttp://ocw.mit.edu
12.158 Molecular Biogeochemistry Fall 2011
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