Sunday, October 25, 2009

Crenarchaeol, derived from Crenarchaea

Crenarchaeol derives from Crenarchaea, linguistically and biochemically. Crenarchaea, a taxonomic grouping of archaea, are autotrophic organisms that are widespread in both surface and deep waters of the oceans [1].
Crenarchaeol, a glycerol dibiphytantyl glycerol tetraether (GDGT) that plays a critical role in the membrane structure of planktonic crenarchaea, was named in 2001 by Jaap Sinninghe Damsté of the Netherlands Institute of Sea Research on the North Sea Island of Texel [4-6], when he and colleagues isolated the compound and identified its structure using two-dimensional nuclear magnetic resonance spectroscopy [1]:
It [crenarchaeol] was distinguished from the other ring-containing tetraethers by a biphytanyl chain that had a six-carbon ring in addition to two of the usual five-carbon rings. Damsté christened the compound “crenarchaeol” and, noting that the six-carbon ring created a sort of bulge in the middle of the tetraether, teamed up with theoretical chemists from the University of Amsterdam to create a molecular model of an archaeal membrane structure with the new compound as core lipid. The result offered one possible solution to the apparent paradox of cold water crenarchaea: whereas the five-carbon rings made the biphytanyl chains fit together more snugly in a dense structure, addition of crenarchaeol with its bulging six-carbon ring kept them from packing together too closely and would, conceivably, allow the membrane to maintain its fluidity at low temperatures.
References and interesting links
[1] Susan M. Gaines, Geoffrey Eglington, and Jürgen Rullkötter: Echoes of LifeWhat Fossil Molecules Reveal about Earth History. Oxford University Press, New York, 2009; see, for example, pages 215-217 and glossary.
[2] Jack R. Holt: Introduction to the Kingdom Crenarchaea.
[3] Sue Barnsand Siegfried Burggraf: Crenarchaeota.
[4] J. S. Sinninghe Damsté
, S. Schouten, E. C. Hopmans, A. C. T. Duin and J. A. J. Geenevasen: Crenarchaeol: the characteristic core glycerol dibiphytanyl glycerol tetraether membrane lipid of cosmopolitan pelagic crenarchaeots. J. Lipid Res. 2002, 43, pp. 1641-1651.
DOI: 10.1194/jlr.M200148-JLR200.
J. S. Sinninghe Damsté, W. I. C. Rijpstra, E. C. Hopmans, F. G. Prahl, S. G. Wakeham and S. Schouten: Distribution of Membrane Lipids of Planktonic Crenarchaeota in the Arabian Sea. Appl. Env. Microbiol. 2002, 68, pp. 2997-3002.
DOI: 10.1128/AEM.68.6.2997-3002.2002.

[6] S. Schouten, E. C. Hopmans, E. Schefuß and J. S. Sinninghe Damsté: Distributional variations in marine crenarchaeotal membrane lipids: a new tool for reconstructing ancient sea water temperatures? Earth Planet Sci. Lett. 2002, 204, pp. 265-274. PDF-version.

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