DISSOCIATIVE THERMAL INACTIVATION, STABILITY, AND ACTIVITY OF OLIGOMERIC ENZYMES

Citation
Om. Poltorak et al., DISSOCIATIVE THERMAL INACTIVATION, STABILITY, AND ACTIVITY OF OLIGOMERIC ENZYMES, Biochemistry, 63(3), 1998, pp. 303-311
Citations number
12
Categorie Soggetti
Biology
Journal title
ISSN journal
00062979
Volume
63
Issue
3
Year of publication
1998
Pages
303 - 311
Database
ISI
SICI code
0006-2979(1998)63:3<303:DTISAA>2.0.ZU;2-2
Abstract
Results of kinetic studies on dissociative thermal inactivation of oli gomeric enzymes are discussed. Dissociative thermal inactivation is th e process in which the kinetically irreversible protein change is prec eded by a reversible stage of oligomer dissociation. In experiments, t his is demonstrated by the dependence of inactivation rate on total pr otein concentration. This paper gives the relations which allow the ca lculation from experimental data the following physicochemical constan ts which characterize the stability of oligomeric enzymes: the constan t for the rate of irreversible change of monomeric protein, the equili brium constant for dimer dissociation, and the tate constant for dimer dissociation. The problem of a ''conformational lock'', the contact b etween protein globules that admits a multistep destruction of active oligomer and explains the induction period occurring in kinetic therma l inactivation curves, is discussed. The X-ray structural analyses for several dimeric enzymes, i.e., alkaline phosphatase (EC 3.1.3.1) from E. coli, alcohol dehydrogenase (EC 1.1.1.1) from horse liver, and bak er's yeast enolase (EC 4.2.1.11), explain why they lose catalytic acti vity during the dissociation of the protein into monomers and also pro vide a physically reasonable picture of the structure of their conform ational lock. Also, these data support the kinetic scheme used to desc ribe the dissociative inactivation of dimeric enzymes.