Molecular adaptations of enzymes from psychrophilic organisms

Molecular adaptations of enzymes from psychrophilic organisms The dominating adaptative character of enzymes from cold-evolving organisms is their high turnover number ( k cat ) and catalytic efficiency ( k cat K m ), which compensate for the reduction of chemical reaction rates inherent to low temperatures. This optimization of the catalytic parameters can originate from the highly flexible structure of these proteins providing enhanced abilities to undergo conformational changes during catalysis at low temperatures. Molecular modelling of the 3-D structure of cold-adapted enzymes reveals that only subtle modifications of their conformation can be related to the structural flexibility. The observed structural features include: 1) the reduction of the number of weak interactions involved in the folded state stability like salt bridges, weakly polar interactions between aromatic side chains, hydrogen bonding, arginine content and charge-dipole interactions in α-helices; 2) a lower hydrophobicity of the hydrophobic clusters forming the core of the protein; 3) deletion or substitution of proline residues in loops or turns connecting secondary structures; 4) improved solvent interactions with a hydrophilic surface via additional charged side chains; 5) the occurence of glycine clusters close to functional domains; and 6) a looser coordination of Ca 2+ ions. No general rule emerges from the molecular changes observed; rather, each enzyme adopts its own strategy by using one or a combination of these altered interactions. Enzymes from thermophiles reinforce the same type of interactions indicating that there is a continuity in the strategy of protein adaptation to temperature. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Comparative Biochemistry and Physiology Part A: Physiology Elsevier

Molecular adaptations of enzymes from psychrophilic organisms

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Publisher
Elsevier
Copyright
Copyright © 1997 Elsevier Ltd
ISSN
0300-9629
eISSN
1879-1115
DOI
10.1016/S0300-9629(97)00011-X
Publisher site
See Article on Publisher Site

Abstract

The dominating adaptative character of enzymes from cold-evolving organisms is their high turnover number ( k cat ) and catalytic efficiency ( k cat K m ), which compensate for the reduction of chemical reaction rates inherent to low temperatures. This optimization of the catalytic parameters can originate from the highly flexible structure of these proteins providing enhanced abilities to undergo conformational changes during catalysis at low temperatures. Molecular modelling of the 3-D structure of cold-adapted enzymes reveals that only subtle modifications of their conformation can be related to the structural flexibility. The observed structural features include: 1) the reduction of the number of weak interactions involved in the folded state stability like salt bridges, weakly polar interactions between aromatic side chains, hydrogen bonding, arginine content and charge-dipole interactions in α-helices; 2) a lower hydrophobicity of the hydrophobic clusters forming the core of the protein; 3) deletion or substitution of proline residues in loops or turns connecting secondary structures; 4) improved solvent interactions with a hydrophilic surface via additional charged side chains; 5) the occurence of glycine clusters close to functional domains; and 6) a looser coordination of Ca 2+ ions. No general rule emerges from the molecular changes observed; rather, each enzyme adopts its own strategy by using one or a combination of these altered interactions. Enzymes from thermophiles reinforce the same type of interactions indicating that there is a continuity in the strategy of protein adaptation to temperature.

Journal

Comparative Biochemistry and Physiology Part A: PhysiologyElsevier

Published: Nov 1, 1997

References

  • Protein stability
    Baldwin, R.L.; Eisenberg, D.
  • A structural role for arginine in proteins: Multiple hydrogen bonds to backbone carbonyl oxygens
    Borders, C.L.; Broadwater, J.A.; Bekeny, P.A.; Salmon, J.A.; Lee, A.S.; Eldridge, A.M.; Pett, V.B.
  • Molecular mechanisms of temperature compensation in poikilotherms
    Hazel, J.R.; Prosser, C.L.

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