Inactivation kinetics of beta-N-acetyl-D-glucosaminidase from green crab (Scylla serrata) in dioxane solution.
Beta-N-acetyl-D-glucosaminidase (NAGase, EC.3.2.1.52), which catalyzes the cleavage of N-acetylglucosamine polymers, is a composition of chitinase and cooperates with endo-chitinase and exo-chitinase to disintegrate chitin into N-acetylglucosamine (NAG). In this investigation, A NAGase from green crab (Scylla serrata) was purified and the effects of dioxane on the enzyme activity for the hydrolysis of p-Nitrophenyl-N-acetyl-beta-D-glucosaminide (pNP-NAG) were studied. The results show that appropriate concentrations of dioxane can lead to reversible inactivation of the enzyme and the inactivation is classified as mixed type. The value of IC50, the dioxane (inactivator) concentration leading to 50% activity lost, is estimated to be 0.68%. The kinetics of inactivation of NAGase in the appropriate concentrations of dioxane solution has been studied using the kinetic method of the substrate reaction. The rate constants of inactivation have been determined. The results showed that k+0 is much larger than k'+0, indicating the free enzyme molecule is more fragile than the enzyme-substrate complex in the dioxane solution. It is suggested that the presence of the substrate offers marked protection of this enzyme against inactivation by dioxane.
Xie
Jin-Jin
JJ
Key Lab of Ministry of Education for Cell Biology and Tumor Cell Engineering, School of Life Sciences, Xiamen University, Xiamen 361005, China.
Chen
Chao-Qi
CQ
Yan
Ya-Wen
YW
Zhang
Ji-Ping
JP
Lin
Jian-Cheng
JC
Wang
Qin
Q
Zhou
Han-Tao
HT
Chen
Qing-Xi
QX
D000116:Acetylgalactosamine / Q000031:analogs & derivatives / Q000737:chemistry; D000118:Acetylglucosaminidase / Q000037:antagonists & inhibitors / Q000737:chemistry*; D000818:Animals; D060829:Arthropod Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry*; D003386:Brachyura / Q000201:enzymology*; D004146:Dioxanes / Q000737:chemistry*; D006868:Hydrolysis; D007700:Kinetics; D012996:Solutions; D012997:Solvents / Q000737:chemistry*
D060829:Arthropod Proteins; D004146:Dioxanes; D012996:Solutions; D012997:Solvents; C014123:4-nitrophenyl-2-acetamido-2-deoxygalactopyranoside; D000118:Acetylglucosaminidase; C025223:1,4-dioxane; D000116:Acetylgalactosamine