海洋细菌L_1-9菌株蛋白酶的初步纯化及其酶学性质研究

Purification and characteristic of a proteinase produced by marine bacterium strain L_1-9

采用硫酸铵沉淀的方法对海洋细菌L1-9菌株产生的蛋白酶进行了初步纯化并对酶学性质进行了测定。结果表明,硫酸铵饱和度由30%升高到80%,随着浓度的增加,沉淀的蛋白酶活性逐渐增强,硫酸铵饱和度为80%时,酶活性达到最高为128.3 U/mL。而上清液的酶活性随着硫酸铵饱和度的增加而下降。对该菌株蛋白酶的酶学性质的研究结果表明:该酶最适反应温度为40℃,在50℃以下保温20 min酶活仍较高,在60℃以上酶活减弱;酶反应最适pH值为7.0,酶活性在pH值5.0～7.0时比较稳定,而在4.0>pH>9.0时酶活性下降较快;金属离子(5 mmol/L)Na+、K+能提高蛋白酶活性,Ag+、Zn2+、Cu2+、Fe3+对蛋白酶活性有抑制作用。

The protease secreted by a marine bacterium strain L1-9 was purified with ammonia sulfate, and the characteristics of this enzyme was investigated. It showed that the enzymatic activity of the sediment protease was increased with the increment of ammonia sulfate concentration from 30% to 80%, and the highest activity （128.3U/ml） was obtained at 80%. However, the activity of the supematant was decreased with the enhancement of ammonia sulfate concentration. The optimal temperature and pH of this enzyme were 40℃ and 7.0, respectively. Na^＋, K^＋ （5 mmol/l） can increase the activity, while Ag^＋, Zn^2＋, Cu^2＋, Fe^3＋ can inhibite the acitivity.