Inhibitory kinetics of mercuric ion on the activity of beta-N-acetyl-D-glucosaminidase from green crab (Scylla serrata).
Chemical modification of p-chloromercuribenzoate (PCMB) on beta-N-acetyl-d-glucosaminidase (NAGase, EC 3.2.1.52) from green crab (Scylla serrata) has been studied. The results show that sulfhydryl group is essential for the activity of the enzyme. Inhibitory kinetics of the enzyme by mercuric chloride (HgCl2) has been studied using the kinetic method of the substrate reaction during inhibitor of enzyme. The kinetic results show that the inhibition of the enzyme by mercuric ion (Hg2+) at lower than 1.0 microM is a reversible reaction with residual activity and the inhibition belongs to be competitive. The inhibition kinetics model of Hg2+ on the enzyme was set up and the microscopic rate constants were determined and the data obtained were well fitted with the model. It was also turned out that only one molecule of HgCl2 binds to the enzyme molecule to lead the enzyme lose its activity. The above results suggest that the cysteine residue is essential for activity and is situated at the active site of the enzyme.
Xie
Jin-Jin
JJ
Key Laboratory of Ministry of Education for Cell Biology and Tumor Cell Engineering, Department of Biochemistry and Biotechnology, School of Life Sciences, Xiamen University, Xiamen, China.
Chen
Qing-Xi
QX
Zhang
Ji-Ping
JP
Wang
Qin
Q
Yang
Xue-Min
XM
D000117:Acetylglucosamine / Q000031:analogs & derivatives / Q000378:metabolism; D000118:Acetylglucosaminidase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D003386:Brachyura / Q000201:enzymology*; D020134:Catalytic Domain; D003545:Cysteine / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006868:Hydrolysis; D066298:In Vitro Techniques; D007700:Kinetics; D008627:Mercuric Chloride / Q000494:pharmacology*
D004791:Enzyme Inhibitors; C014124:4-nitrophenyl-N-acetyl-2-deoxyglucopyranoside; D008627:Mercuric Chloride; D000118:Acetylglucosaminidase; D003545:Cysteine; D000117:Acetylglucosamine