A strain was isolated from intestinal of shellfish in Weihai waters which could produce extracellular alkaine pro-tease,and was identified as Vibrio sp. 21Z1 by 16S rDNA analysis. The purified alkaine enzyme 21Z1 was obtained through ammonium sulfate precipitation,dialysed and Sephadex-G100 column chromatography. Its molecular weight was determined as about 31 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE)analysis. The re-sults show that the optimal temperature of this enzyme is 40 ℃,and it is stable at 20 ～ 40 ℃. The optimal pH of this en-zyme is 8.5,and it is stable at pH ranging from 8.5 ～11.0. Na +,K +,Ca2 +,and Mn2 + have effect on its enzyme activity while Fe2 +,Fe3 +,Zn2 + and Cu2 + have various degrees of inhibition effect upon this enzyme. The salt tolerance test of enzyme 21Z1 exhibits the residual protease activity remains more than 62％ at 4 mol/ L concentration of Na +,so alkaine protease 21Z1 has good salt resistance.%由威海海域贝类肠道中分离出一株产胞外碱性蛋白酶的细菌,经16S rDNA分析鉴定为弧菌21Z1.该菌发酵液上清经60％饱和度的硫酸铵溶液沉淀、透析、Sephadex-G100分子筛层析等步骤,获得电泳纯的21Z1碱性蛋白酶,聚丙烯酰胺凝胶电泳(SDS-PAGE)显示其分子量约为31 kDa.酶学性质测定结果显示:该酶最适反应温度为40℃,在20～40℃稳定;最适反应pH为8.5,在pH=8.5～11.0间稳定;Na+、K+、Ca2+、Mn2+对该酶具有激活作用,Fe2+、Fe3+、Zn2+及Cu2+则不同程度地抑制其活性;该酶的耐盐性检测结果显示,在Na+浓度为4 mol/L时,残余酶活在62％以上,表明21Z1碱性蛋白酶具有较强的耐盐性.
展开▼
