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Geophysical Monograph Series

 

Keywords

  • Deep-sea ecology—Congresses
  • Mid-ocean ridges—Congresses

Article

GEOPHYSICAL MONOGRAPH SERIES, VOL. 144, PP. 25-39, 2004

The stability of biomolecules and the implications for life at high temperatures

R. M. Daniel, R. van Eckert, J. F. Holden, J. Truter, and D. A. Crowan

The thermal stability of two key groups of biological molecules, intracellular small molecules and metabolites and the major classes of macromolecules, are examined to estimate the upper temperature limit for life at the subcellular level. Certain small molecules and metabolites are unstable in vitro at the growth temperatures of the hyperthermophiles in which they are found. This instability appears to be dealt with in vivo by a range of mechanisms including rapid turnover, metabolic channelling and local stabilization. Evidence to date suggests that proteins have the potential to be stable at substantially higher temperatures than those known to support life, but evidence concerning degradative reactions above 100°C is slight. DNA duplex stability is apparently achieved at high temperature by elevated salt concentrations, polyamines, cationic proteins, and supercoiling rather than manipulation of G+C ratios. RNA stability is enhanced by covalent modification, and secondary structure is probably also critical. The diether-linked lipids, which make up the monolayer membrane of most organisms growing above 85°C are chemically very stable and seem potentially capable of maintaining membrane integrity at much higher temperatures. However, the in vivo implications of the in vitro instability of biomolecules are difficult to assess, and in vivo data are rare.

Citation: Daniel, R. M., R. van Eckert, J. F. Holden, J. Truter, and D. A. Crowan (2004), The stability of biomolecules and the implications for life at high temperatures, in The Subseafloor Biosphere at Mid-Ocean Ridges, Geophys. Monogr. Ser., vol. 144, edited by W. S. Wilcock et al., pp. 25–39, AGU, Washington, D. C., doi:10.1029/144GM03.

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