Inhibitory Kinetics of beta-N-Acetyl-D-glucosaminidase from Green Crab (Scylla serrata) by Zinc Ion
- 生命科学－已发表论文 
Heavy metal pollution such as chromium and zinc in the seawater has been increasing in recent years in the China Sea. Marine shellfish such as prawn and crab are sensitive to this pollution. beta-N-Acetyl-D-glucosaminidase (NAGase, EC 188.8.131.52) catalyzes the cleavage the oligomers of N-acetylglucosamine (NAG) into the monomer. In this study, taking p-nitrophenyl-N-acetyl-beta-D-glucosaminide (pNP-NAG) as substrate, the effects of Zn2+ on NAGase from green crab (Scylla serrata) have been studied. The results showed that appropriate concentrations of zinc could lead to reversible inhibition on the enzyme, and the IC50 has been estimated to be 0.5 +/- 0.012 mM. Furthermore, it has been shown that Zn2+ could reduce the thermal stability of NAGase depending on the concentration of Zn2+ The inhibitory kinetics of zinc on the enzyme in the appropriate concentrations has been studied using the kinetic method of substrate reaction. The inhibition model has been set up, and the rate constants have been determined. The results showed that Zn2+ was a mixed-type inhibitor of NAGase and that it could combine at the free enzyme and the enzyme-substrate active sites.