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

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.