Inhibition kinetics of hydrogen peroxide on beta-n-acetyl-D-glucosaminidase from prawn (Penaeus vannamei).
The effects of hydrogen peroxide (H2O2) on prawn NAGase activity for the hydrolysis of pNP-beta-D-GlcNAc have been studied. The results show that H2O2 can reversible inhibit the enzyme (IC50 = 0.85 M) and the inhibition is of a mixed type. The kinetics show that k+o is much larger than k+0, indicating the free enzyme is more susceptible than the enzyme-substrate complex in the H2O2 solution. It is suggested that the presence of the substrate offers marked protection against inhibition by H202. Changes of activity and conformation of the enzyme in different concentrations of H202 have been compared by measuring the fluorescence spectra and residual activity and show that the change of conformation is more rapidly than that of the residual activity, which implies that the whole conformation of the enzyme changes more rapidly than the conformation of the active centre of the enzyme in the H2O2 solution.
The 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 361005, P R. China.
Xiao-Lan
XL
Xie
Min
M
Gong
Qing-Xi
QX
Chen
D000118:Acetylglucosaminidase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D006868:Hydrolysis; D007700:Kinetics; D033561:Penaeidae / Q000201:enzymology*; D011487:Protein Conformation / Q000187:drug effects
D006861:Hydrogen Peroxide; D000118:Acetylglucosaminidase