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Indexed by:期刊论文

Date of Publication:2001-10-01

Journal:JOURNAL OF ENZYME INHIBITION

Included Journals:Scopus、SCIE、PubMed

Volume:16

Issue:4

Page Number:313-319

ISSN No.:8755-5093

Key Words:alkaline phosphatase; kinetics; inactivation; zinc ion

Abstract:Ova pertusa Kjellm alkaline phosphatase (EC 3.3.3.1) is a metalloenzyme, the active site of which contains a tight cluster of two zinc ions and one magnesium ion. The kinetic theory described by Tsou of the substrate reaction during irreversible inhibition of enzyme activity has been employed to study the kinetics of the course of inactivation of the enzyme by EDTA. The kinetics of the substrate reaction at different concentrations of the substrate p-nitrophenyl phosphate (PNPP) and inactivator EDTA indicated a complexing mechanism for inactivation by, and substrate competition with, EDTA at the active site. The inactivation kinetics are single phasic, showing that the initial formation of an enzyme EDTA complex is a relative rapid reaction, following by a slow inactivation step that probably involves a conformational change of the enzyme. The presence of Zn2+ apparently stabilizes an active-site conformation required for enzyme activity.