维生素对凡纳滨对虾N-乙酰-β-D-氨基葡萄糖苷酶的效应研究

Effects of some vitamins on the activity of NAGase from Pacific white shrimp(Litopenaeus vannamei)

以凡纳滨对虾中提取的N-乙酰-β-D-氨基葡萄糖苷酶(NAGase,EC 3.2.1.52)为研究对象,以对-硝基苯-N-乙酰-β-D-氨基葡萄糖苷(pNP-NAG)为底物,考察了几种养殖常用维生素对该酶活力的影响.结果表明,VB12、烟酸、核黄素等对酶活力基本上没有影响;而VB1、VB6、抗坏血酸等对该酶活力均有不同程度的抑制作用.随着抑制剂浓度增大,酶活力呈指数下降,测定导致酶活力下降50%的抑制剂浓度(IC50)分别为16.0、13.5、37.5mmol/dm3.进一步研究了VB6的抑制作用动力学,结果显示:VB6对酶的抑制作用为非竞争性可逆抑制,其对酶抑制常数(KI)为15.2mmol/dm3.该研究对凡纳滨对虾的人工养殖具有一定的参考价值.

The effects of some vitamins on the activity of N-acetyl-β-D-glucosaminidase （NAGase, EC 3.2.1.52） from Pacific white shrimp （Litopenaeus vannamei）were studied. The results indicated that vitamin Bn ,vitamin PP and vitamin B2 had little effect on the enzyme activity. But vitamin B1 , vitamin B6 and vitamin C inhibited the enzyme activity at different levels. The NAGase activity deereased exponentially with increasing concentrations. The IC50s of vitamin B1 ,vitamin B6 and vitamin C were determined as 16. 0, 13.5 and 37.5mmol/dm^3 ,respectively. The inhibitory kinetics of vitamin B6 on the enzyme were studied in details. It showed that the inhibition of vitamin B6 to NAGase were reversible and noncompetitive. The inhibition constant（K1 ）, 15.2mmol/dm^3, was determined. The data from this study can be usful to the aquaculture of Pacific white dolphin.