Kinetics of inhibition of green crab (Scylla serrata) alkaline phosphatase by vanadate.
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.
Chen
Q X
QX
Department of Biology, Xiamen University, Xiamen, 361005, People's Republic of China.
Zheng
W Z
WZ
Lin
J Y
JY
Cai
Z T
ZT
Zhou
H M
HM
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*
D014638:Vanadates; D000469:Alkaline Phosphatase