摘要
研究甲醛对锯缘青蟹N-乙酰氨基葡萄糖苷酶(NAGase EC 3.2.1.52)活力的影响,结果表明:随着甲醛浓度的增大,酶活力呈指数下降,导致酶活力下降50%的甲醛浓度(失活半衰期,IC50)为0.60 mol/L.酶在低浓度甲醛溶液中的失活过程显示为可逆失活.用底物反应动力学方法考察酶在甲醛溶液中的失活动力学,测定游离酶(E)和酶-底物络合物(ES)在甲醛溶液中失活的微观速度常数,并比较游离酶(E)和酶-底物络合物(ES)的正向反应的微观失活速度常数k+0>k′+0,表明底物对酶被甲醛的失活作用有一定的保护作用.正向的失活速度常数k+0和k′+0随着甲醛浓度的增大而增大,而逆向的速度常数k-0随着甲醛浓度的增大而减小,表明随着甲醛浓度的增大,酶变性越来越快,而活力恢复越来越难.
The effect of formaldehyde on N-acetyl-β-D-glueosaminidase （NAGase） from green crab （Scylla serrata） was investigated. The results showed that formaldehyde could inactivate the enzyme activity with IC50 of 0.6 mol/L. The inactivation of enzyme by formaldehyde is a reversible reaction with remaining enzyme activity. Inactivation kinetics of the enzyme in formaldehyde solutions was studied using the Tsou＇s method of the substrate reaction,and the microscopic rate constants of inactivation for the free enzyme and the enzyme-substrate complex were determined. Comparison of these rate constants was made,the result showed that k＋0 was larger than k＇＋0 ,indicating a marked protective effect of the substrate on the inactivation reaction of this enzyme with formaldehyde. Moreover,the value of forward inactivation rate constant of the enzyme （k＋0 and k＇＋0 ） increased with increasing formaldehyde concentration while the value of reverse reaction （k-0） decreased. The results suggested the inactivation of enzyme in higher concentration of formaldehyde would be more difficultly reversible.
出处
《厦门大学学报（自然科学版）》
CAS
CSCD
北大核心
2006年第1期98-101,共4页
Journal of Xiamen University：Natural Science
基金
国家自然科学基金(40576066)资助
关键词
锯缘青蟹
N-乙酰氨基葡萄糖苷酶
甲醛
失活动力学
Green crab （Scylla serrata ）
N-acetyl-b-D-glucosaminidase
formaldehyde
inactivation kinetics
