Cellular and Molecular Life Sciences CMLS

, Volume 58, Issue 9, pp 1216–1233 | Cite as

How do thermophilic proteins deal with heat?

  • S. Kumar
  • R. Nussinov


Recent years have witnessed an explosion of sequence and structural information for proteins from hyperthermophilic and thermophilic organisms. Complete genome sequences are available for many hyperthermophilic archaeons. Here, we review some recent studies on protein thermostability along with work from our laboratory. A large number of sequence and structural factors are thought to contribute toward higher intrinsic thermal stability of proteins from these organisms. The most consistent are surface loop deletion, increased occurrence of hydrophobic residues with branched side chains and an increased proportion of charged residues at the expense of uncharged polar residues. The energetic contribution of electrostatic interactions such as salt bridges and their networks toward protein stability can be stabilizing or destabilizing. For hyperthermophilic proteins, the contribution is mostly stabilizing. Macroscopically, improvement in electrostatic interactions and strengthening of hydrophobic cores by branched apolar residues increase the enthalpy change between the folded and unfolded states of a thermophilic protein. At the same time, surface loop deletion contributes to decreased conformational entropy and decreased heat capacity change between the folded and unfolded states of the protein.

Key words. Thermostability; salt bridges; electrostatics; adaptation; protein; temperature; structure. 


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Copyright information

© Birkhäuser Verlag, 2001

Authors and Affiliations

  • S. Kumar
    • 1
  • R. Nussinov
    • 2
  1. 1.Laboratory of Experimental and Computational Biology, NCI-Frederick, Bldg 469, Rm 151, Frederick, Maryland 21702 (USA)US
  2. 2.Intramural Research Support Program-SAIC, National Cancer Institute-Frederick, Frederick Cancer Research and Development Center, Bldg 469, Rm 151, Frederick, Maryland 21702 (USA), Fax + 1 301 846 5598, e-mail: ruthn@ncifcrf.govUS

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