南美白对虾虾头内源酸性蛋白酶的分离纯化及其酶学特性研究

Purification and characteristics of endogenous acid protease from shrimp head of Litopenaeus vannamei

通过10%～50%的硫酸铵盐析和两次柱层析,从南美白对虾虾头的匀浆液中分离纯化出一种内源酸性蛋白酶,经电泳分析测得其分子量为27.45ku,该酶的Km值、Vmax值、最适pH和最适反应温度分别为2.01g/L、26.39μg/min、3.0和30℃。内源酸性蛋白酶的热稳定性较差,Pepstatin A和EDTA对该蛋白酶表现出强烈的抑制作用,Hg+能完全抑制该蛋白酶,但Ca2+却能激活该蛋白酶。据此推断该蛋白酶是一种金属蛋白酶,该酶活性中心含有一些金属离子,其性质类似于胃蛋白酶类。

Endogenous acid protease was purified from a shrimp head homogenate of Litopenaeus vannamei by 10%～50% of ammonium sulfate fractions and twice chromatography.Its molecular weight was estimated to be 27.45ku by SDS-PAGE electrophoresis and its apparent Km,Vmax,optimal pH and optimal temperature for casein were 2.01g/L,26.39μg/min,3.0 and 30℃,respectively.The endogenous acid protease had weak thermostability and could be significantly inhibited by Pepstatin A,EDTA and Hg＋,but activated by Ca2＋.It＇s inferred the protease from Litopenaeus vannamei shrimp head was a kind of Metalloproteases and that activity centers might also contain small amounts of metalions,the property of the enzyme was similar to the pepsin.