Temperature Dependence of the Enzyme-Substrate Recognition Mechanism

• Published in: Journal of biochemistry (Tokyo) Vol. 129; no. 1; pp. 173 - 178
• Main Authors: Ura, Hideaki, Harata, Kazuaki, Matsui, Ikuo, Kuramitsu, Seiki
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.01.2001
• Subjects: aminotransferase; Binding Sites; Crystallography, X-Ray; domain movement; Escherichia coli - enzymology; hyperthermophilic enzyme; Models, Molecular; Protein Conformation; Protein Structure, Tertiary; Pyrococcus - enzymology; Pyrococcus horikoshii; substrate recognition; Substrate Specificity; Temperature; Thermus thermophilus - enzymology; Transaminases - chemistry; Transaminases - metabolism
• ISSN: 0021-924X
• DOI: 10.1093/oxfordjournals.jbchem.a002829

We determined the crystal structure of the liganded form of α-aminotransferase from a hyperthermophile, Pyrococcus horikoshii. This hyperthermophilic enzyme did not show domain movement upon binding of an acidic substrate, glutamate, except for a small movement of the α-helix from Glu16 to Ala25. The ω-carboxyl group of the acidic substrate was recognized by Tyr70* without its side-chain movement, but not by positively charged Arg or Lys. Compared with the homologous enzymes from Thermus thermophilus HB8 and Escherichia coli, it was suggested that the more thermophilic the enzyme is, the smaller the domain movement is. This rule seems to be applicable to many other enzymes already reported.