患红体病的凡纳滨对虾外壳膜NAGase基本性质的改变

Variations in Basic Properties of NAGase from Crustaceous Membrane of Litopenaeus vannamei Suffered from Red-body Disease

分别以健康和患红体病的凡纳滨对虾(Litopenaeus vanname)外壳膜为材料,抽提其N-乙酰-β-D-氨基葡萄糖苷酶(EC3.2.1.52,简称NAGase),测定分析两种来源对虾的外壳膜NAGase的活力和性质的差异.测得健康对虾NA-Gase的活力为34·80Umg-1,而患红体病对虾的活力为38·32Umg-1.结果表明:两种来源对虾的NAGase活力、基本酶学性质等均存在差异.表明对虾患红体病后,外壳膜NAGase的活力、催化反应动力学常数Km和Vm值、活化能均较高,但其最适温度较低,pH稳定性及热稳定性较差.

N-acetyl-β-D-glucosaminidase （ EC 3.2. 1.52, NAGase） was extracted and purified from the crustaceous membranes of both healthy and red-body disease suffering shrimps （ Litopenaeus vannamei ）. The activity of the enzyme from the crustaceous membrane of healthy shrimps was 34. 80 U mg^-1, and that from the ones of red-body-desease was 38.32 U mg^-1. The variations in activities and basic properties of the enzymes between the two kinds of shrimps were investigated. The results showed that the variations existed in the specific activity, optimum temperature and dynamic constants including Km , Vm , and Ea for the hydrolysis of pNP-NAG by the enzymes from the two sources. The activity of NAGase and the kinetic parameters, such as the values of Km, Vm and Ea were higher after the shrimp suffered from red-body disease, but the optimum temperature was relatively low, and pH and thermal stabilities were not so good. Fig 5, Tab 1, Ref 11