title: Kinetics of inhibition of green crab (Scylla serrata) alkaline phosphatase by vanadate.
abstract: Green crab (Scylla serrata) alkaline phosphatase is a metalloenzyme that catalyzes the nonspecific hydrolysis of phosphate monoesters. The kinetics of inhibition of the enzyme by vanadate has been studied. The time course of the hydrolysis of p-nitrophenyl phosphate catalyzed by the enzyme in the presence of different Na3VO4 concentrations showed that, at each Na3VO4 concentration, the rate decreased with increasing time until a straight line was approached, the slopes of the straight lines being the same for all concentrations. The results suggest that the inhibition of the enzyme by Na3VO4 is a slow, reversible reaction with fractional residual activity. The microscopic rate constants were determined for the reaction of the inhibitor with the enzyme. As compared with Na2HPO4 (Ki = 0.95 mM), Na2HAsO4 (Ki = 1.10 mM), and Na2WO4 (Ki = 1.55 mM), the results suggest that Na3VO4 (Ki = 0.135 mM) is a considerably more potent inhibitor than other inhibitors.
authors.affiliation: Department of Biology, Xiamen University, Xiamen, 361005, People's Republic of China.
authors.forename: Q X
authors.initials: QX
authors.lastname: Chen
authors.forename: W Z
authors.initials: WZ
authors.lastname: Zheng
authors.forename: J Y
authors.initials: JY
authors.lastname: Lin
authors.forename: Z T
authors.initials: ZT
authors.lastname: Cai
authors.forename: H M
authors.initials: HM
authors.lastname: Zhou
mesh_terms: D000469:Alkaline Phosphatase / Q000037:antagonists & inhibitors*; D000818:Animals; D003386:Brachyura / Q000201:enzymology*; D006868:Hydrolysis; D007700:Kinetics; D013379:Substrate Specificity; D013997:Time Factors; D014638:Vanadates / Q000494:pharmacology*
chemical_list: D014638:Vanadates; D000469:Alkaline Phosphatase