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
1
Sterols, Eukaryotes and O2
squaleneepoxide
squalene
1.14.99.7 + O2
29
28
O
22
21
26
24
20
18
LANOSTEROL BRANCH
5.4.99.7
5.4.99.8
9
A
3
HO
1.14.13.70 + 3 O2
10
C
B
8
D
27
16
15
7
5
4
cycloartenol
13
14
2
PROTOSTEROLS
2.1.1.41
17
11
1
lanosterol
6
smt1
24-methylenecycloartenol
eburicol
smo1 + 3 O2 , 1.1.1.170, 1.1.1.270
4,4-dimethyl-5?-cholesta-8,14,24-trien-3?-ol
HO
1.14.13.70 + 3 O2
HO
HO
1.3.1.70
4,4-dimethyl-5?-ergosta-8,14,24(28)-trien-3?-ol
cycloeucalenol
5.5.1.9
4,4-dimethyl-5?-cholesta-8,24-dien-3?-ol
HO
HO
HO
1.14.13.72, 1.1.1.170, 1.1.1.270 +3 O2
1.3.1.70
4,4
4,4--dimethylfecosterol
dimethylfecosterol
obtusifoliol
1.14.13.70 + 3 O2
4?-methyl zymosterol
H O
HO
HO
1.14.13.72, 1.1.1..170, 1.1.1.270 +3 O2
1.14.13.72, 1.1.1.170, 1.1.1.270 +3 O2
4?-methylfecosterol
4?-methyl-5?-ergosta-8,14,24(28)-trien-3?-ol
1.3.1.70
zymosterol
HO
HO
1.14.13.72, 1.1.1..170, 1.1.1.270 +3 O2
HO
5.3.3.5
fecosterol
4?-methylfecosterol
5.3.3.5
5?-cholesta-7,24-dien-3?-ol
HO
HO
erg2
HO
1.3.1.72
24-methylenelophenol
24methylenelophenol
smt2
episterol
lathosterol
HO
erg3+ O2
HO
HO
1.3.3.2 + O2
24-ethylenelophenol
smo2 + 3 O2 , 1.1.1.170, 1.1.1.270
5,7,24(28)-ergostatrienol
5,7,24(28)ergostatrienol
7-dehydro-cholesterol
HO
HO
HO
1.3.1.21
erg5 + O2
24-ethylenelathosterol
5,7,22,24(28)-ergostatetraenol
5,7,22,24(28)ergostatetraenol
cholesterol
HO
1.3.3.2 + O2
HO
HO
1.3.1.71
ergosterol
24-methylene 5-dehydroepisterol
1.3.1.21
HO
HO
isofucosterol
dwf1
HO
12 O2
Burial & diagenesis
11 O2
ergostane
11 O2
cholestane
25
12
CYCLOARTENOL BRANCH
19
H O
23
sitosterol
HO
sitosterane
The effect of oxygen on biochemical networks and the evolution of complex life. Jason Raymond and Daniel Segre' Science 311, 1764-1767 (2006)
Cholesterol
This image has been removed due to copyright restrictions. squalene hopene,
tetrahymanol 3
http://prelude.bu.edu/
O2/networks.html
4
Oxidosqualene Cyclase
This image has been removed due to copyright restrictions. 5
Symbiogenesis:
the phylogenetic
tapestry of
eukaryotes
This image has been removed due
to copyright restrictions.
http://www.life.umd.edu/
labs/delwiche/
6
Eukaryote Diversity & Chloroplast Endosymbiosis Anaerobes
stem of tree?
Algae
Forams
Radiolaria
This image has been removed due to copyright restrictions.
Keeling et al. 2005 ©Jacob Waldbauer, 2007
7
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?
ergosterol
24-methyl-5,7,22-trien-3β-ol
HO
cycloartenol
HO
β-sitosterol
24-ethyl-5-en-3β-ol HO
HO
8
stigmasterol
24-ethyl-5,22-dien-3β-ol
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.
HO
red algal
sterol
HO
HO
4a-methyl-24-ethyl­
cholestan-3β-ol
HO
9
sponge
sterol
dinosterol
Oxidosqualene Cyclase Alignment
This image has been removed due to copyright restrictions.
10
Microorganism Major or common sterols Microalgae
Bacillariophyceae
C28D5,22, C28D5,24(28), C27D5, C29D5, C27D5,22
Bangiophyceae
C27D5, C27D5,22, C28D7,22
Chlorophyceae
C28D5, C28D5,7,22, C28D7,22 C29D5,22, C29D5
Chrysophyceae
C29D5,22, C29D5, C28D5,22
Cryptophyceae
C28D5,22
4Me-D0, dinosterol, C27D5, C28D5,24(28)
Dinophyceae
C28D5,7,22, C29D5, C28D7, C29D5,7, C28D7,22
Euglenophyceae
C27D5 (marine) or C29D5 (freshwater)
Eustigmatophyceae
Haptophyceae
C28D5,22, C27D5, C29D5,22, C29D5
Pelagophyceae
C30 D5,24(28), C29D5,22, C29D5, C28D5,24(28)
C28D5, C28D5,24(28), C28D5
Prasinophyceae
C29D5, C28D5,24(28)
Raphidophyceae
C27D5, C27D5,22
Rhodophyceae
Xanthophyceae
C29D5, C27D5
C27D5, C29D5, C27D0, C29D0 (evidence equivocal)
Cyanobacteria:
4Me-D8
Methylotrophic bacteria
C27D5
Other bacteria
C28D5,7,22, C28D7, C28D7,24(28)
Yeasts and fungi
C27D5, C29D5,22, C28D5,22, C29D5,7,22
Thraustochytrids
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.
11
Uncommon Marine Sterols HO
HO
24-methyl-27-nor sterols and stanol
known in sponges: C27 compounds
24-nor sterols
a range of algae & invertbrates: C26
R
H
HO
HOH2C
H H
A-nor sterols
sponges
H
19-nor sterols
R=H, CH3, C2H5, methylene
Δ22 trans unsaturation
probably formed by de-alkylation
of algal sterols
12
Uncommon Marine Sterols (2) HO
HO
Aplysterol
Gorgosterol
13
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 Acetate
Derivativesa
Steryl acetate________Mass spectrum (m/z, relative intensity to
base 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)
14
Sterol Reading #1 Text has been removed due to copyright restrictions.
Please see
http://www.springerlink.com/content/q05172k241v60328
15
Reconstruction of past biota
16
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?
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?
17
This image has been removed
due to copyright restrictions.
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 record
Rose to ecological prominence relatively
recently
These images have been
removed due to copyright
restrictions.
Chl a+c Phytoplankton Diatoms Dinoflagellates Coccolithophorids Picocyanobacteria Prochlorococcus/
Marine Synechococcus 18
Eukaryote Diversity & Chloroplast Endosymbiosis Anaerobes
stem of tree?
Algae
Forams
Radiolaria
This image has been removed due to copyright restrictions.
Keeling et al. 2005 ©Jacob Waldbauer, 2007
19
The Fossil Record of Phytoplankton - one form of bias: where
sediment is deposited
20
Another form of Bias:Age of the Ocean Floor 200
0
NOAA NGDC 21
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
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.
23
Evolutionary Trends from Rocks & Oils: Present-day sample localities This image has been removed due to copyright restrictions. 24
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
25
PaleoLatitude vs Carbonate-Sourced Oils
1.4
carbonate
marl
shale
1.2
C29/C30H
1.0
0.8
0.6
0.4
0.2
-80
-60
-40
-20
0
Paleo Latitude
26
20
40
60
80
Pentacyclic Terpane Ratios 0.60
0.55
0.50
C31R/H
0.45
0.40
0.35
0.30
0.25
carbonate
marl
shale
lacustrine
0.20
0.15
0.10
0.2
0.4
0.6
0.8
C29/H
27
1.0
1.2
1.4
• 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 28
C28/C29 Sterane Ratios: The Rise of Modern Plankton
29
Dinoflagellate Biomarkers-Petroleum Record 1.0
carbonate
marl
distal shale
lacustrine
End Cretaceous
End Permian
End Proterozoic
0.9
L12
DS21
M1
C3
0.8
DS4
DS5
DS2
DS9
Aromatic Dinosteranes (3/3+6)
DS3
0.7
DS19
M2
DS20
DS16
DS13
DS10
DS1
C2
DS8
DS12
DS42
DS54
DS44
DS43
C4
DS40
DS34
C8
DS24 DS37
DS26
DS38
DS27
DS17
C1
DS48
DS47
L16
C5 DS39
C6
L13
L11
DS15
DS6
0.6
M4
M3
C7
L15
DS53
L20
L14 DS45
C15
L18
DS52
L17 C14 DS46
C16 DS50
DS51
L19
C10
C9
DS49
C17
DS41
C12
DS65
M6
M5
DS14
M9
M8
C18
DS11
L24
0.5
L4
0.4
L7
0.3
L1
L6
L9
L3
L8
0.2
L2
L23
L5
0.1
DS56
L21
M7
C21
C22
C19
C20
DS55
0.0
0
50
100
150
200
250
300
350
Source Rock Age (mybp)
30
DS57
DS61
DS60
DS59
400
DS64
DS62
DS63
450
DS68
DS67
DS66
C25
DS69
500
DS73
M10
550
DS70
DS71
DS72
DS74
600
Aromatic dinosteroids/2+3-methyls
Distribution of
dinosteroids in
Phanerozoic
sediments
This image has been removed
due to copyright restrictions. Moldowan and Talyzina
Science 281,168-1170, 1998
31
C26 steranes
21-nor
Unknown source 24-nor
Unknown source 27-nor
Unknown source 32
Secular Change in C26 Sterane Abundance
Application 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
in reconstructing the evolution of diatoms.
24-nor
HO
217
Diatom sterane
Diatom sterol
33
C26 steranes elution pattern This image has been removed
due to copyright restrictions.
Moldowan et al GCA 55, 1065, 1991
34
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
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
C20 HBI
VOL 304
SCIENCE
This image has been removed
due to copyright restrictions.
C25
HBI
•Identified in the diatom genera
Rhizosolenia, Haslea, Navicula, and
Pleurosigma only
•Biological products have 1-6
unsaturations; fossils fully saturated
36
C30 Desmethylsteranes 37
C30 Desmethyl Steranes Oil from Southern Oman
NZ Kora
24-n-propylcholestanes
414
217
OM20
24-i-propylcholestanes
414
217
59:00
1:00:00
1:01:00
38
ααα
20S
1:02:00
αββ
20R+S
ααα
20R
1:03:00
1:04:00
Time
C30 Desmethyl Steranes Eastern Siberia Oils
ES36
414
217
ES89
414
59:00
1:00:00
i/n>1
217
1:01:00
i/n<1
1:02:00
39
1:03:00
1:04:00
Time
Stratigraphic
column of Huqf
Supergroup
withrepresentativ
e
lithology,
biostratigraphy
and
geochronologica
l constraints.
This image has been removed
due to copyright restrictions. GD Love et al. Nature 457, 718-721 (2009) doi:10.1038/
nature07673 40
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)
41
Hydropyrolysis apparatus
Thermocouple
High pressure
hydrogen
Reactor tube
Sample bed with
dispersed Mo catalyst
Electrical
connectors
Temp prog.
amb. – 500oC @ 8oC/min
H 2 pressure
15 MPa
sweep gas flow
10 dm3/min
Gas collection
And measurement
Mass-flow
controller
Cold
trap
Pressure
transducer
Temperature-programmed, open-system pyrolysis (fast residence time of volatile
42
Comparison of free and kerogen-bound hydrocarbons TICs of saturates for a Minassa-1(A1C) sample 05 May 17 10
17
100
std.
19
21
Ph
15
Free saturated hydrocarbons
*
23
* = std.
25
%
27
i18 Pr
x
x
2
05 May 31 08
17
100
x
x
x
hopane/sterane region
29
x
31
x x
19
HyPy of Kerogen
21
15
23
Ph %
25
i18
Pr
x
x
x
x
x
27
x
x x
x
hopane/sterane region
29
31
2
15.00
20.00
25.00
30.00
35.00
40.00
45.00
50.00
55.00
Numbers refer to carbon chain lengths of n-alkanes
X= series of mid-chain methylalkanes (unknown origin)
60.00
65.00
70.00
75.00
80.00
85.00
Time
90.00
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.
GD Love et al. Nature 457, 718-721 (2009) doi:10.1038/
nature07673 44
This image has been removed
due to copyright restrictions.
45
2- & 3-methylsteranes
21418 b/c +std 50ng/1000ul
03100216
100
62.11
60.82
%
414.423 > 231.212
62.82
63.06
58.6459.04
58.15
65.12 65.63
0
03100216
100
%
4-methylsteranes
62.80
414.423 > 217.196
61.32
57.57 58.62
59.81
55.95 56.86
52.24 53.10
MRM –GCMS
showing C30 steranes
of a marine sediment
63.00
64.23
0
03100216
100
61.20
400.407 > 217.196
61.14
404.432 > 221.221
59.91
56.11
%
57.12
58.76
55.39
0
03100216
100
%
51.57
55.02
58.23
64.05
0
52.50
55.00
57.50
60.00
62.50
65.00
67.50
46
Time
70.00
2- & 3­
alkylsteranes Note the exact
co-elution of the
four synthetic
isomers with the
equivalent
peaks of the
Phosphoria oil
This image has been removed
due to copyright restrictions.
47
2- & 3­
alkylsteranes Note the different isomer preference for
marine vs
lacustrine
sediments
This image has been removed
due to copyright restrictions.
48
MIT OpenCourseWare
http://ocw.mit.edu
12.158 Molecular Biogeochemistry
Fall 201
For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms.
49