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Cumulative Effect of Intragenic Amino Acid Replacements on Thermostability of a Protein

  • Shuichi Aiba
Conference paper

Abstract

The marginal net stability of a folded protein is considered to rest upon a small difference among large compensating, individual forces. Therefore, the net free energy of stabilization of proteins is unexpectedly small, ~40 kJ mol−1. Meanwhile, the contribution of individual forces such as hydrogen bonds and salt bridges to the stabilization are evaluated as 4 to 12 kJ mol−1, and several additional forces are thought to be sufficient to account for the extra thermostability of thermophilic proteins. The native conformation of a protein is determined by the totality of interatomic interactions and hence, by the amino acid sequence. If a few amino acid residues which individually contribute to the stabilization could be implemented concurrently into the sequence, the multiple replacement would enhance an overall stability of the protein molecule. Herein a report on concrete evidence in favor of this argument will be presented. Thermal inactivation kinetics and proteolytic resistance for mutants of a kanamycin nucleotidyltransferase revealed that a few intragenic amino acid replacements stabilized the protein cumulatively. This work demonstrates not only the feasibility of elevating a protein’s thermostability but also a way to better understanding of forces and interactions that are responsible for the protein stability.

Keywords

Hydrogen Bond Amino Acid Sequence Amino Acid Residue Protein Molecule Cumulative Effect 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Copyright information

© Springer-Verlag Berlin Heidelberg 1989

Authors and Affiliations

  • Shuichi Aiba
    • 1
  1. 1.Department of Fermentation TechnologyOsaka University, Faculty of EngineeringSuita-shi, OsakaJapan

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