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A. V. Stepashkina, A. S. Yasnaya, A. I. Berezin, V. I. Tishkov
Influence
of pH On
thermal stability of penicillin acylase from Alcaligenes faecalis
Abstract
Penicillin G acylase (PA, EC 3.5.1.11) from Alcaligenes faecalis
(AfPA) is one of the most thermostable bacterial penicillin acylases. However
the systematic data about thermal stability of AfPA are not presented in
literature. Systematic study of influence of pH on thermal stability of AfPA
was done in pH range 7.5–9.5. It was found that in all pH range studied enzyme
inactivation follows the first order kinetics. Dependence of inactivation rate
constant on pH has S-shape with inflection point at pH 8.3–8.5. Temperature
dependences of inactivation rate constant at four pH were obtained and
activation parameters DH# and DS# were calculated for each pH value. Decrease of both
values, DH# and DS#, with pH growth shows
that minimum one iogenic group is essential for the enzyme thermal stability.
Copyright (C) Chemistry Dept., Moscow State University, 2002
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