芽孢杆菌NCB-01胞外蛋白酶酶学特性的初步研究

该实验对来自于渤海海域沉积物的芽孢杆菌NCB-01分泌的胞外蛋白酶的酶学特性进行了初步研究。结果表明，该蛋白酶的最适作用温度为60 ℃，最适pH值为8.0，在50 ℃以下及pH值7.0～9.0的范围内酶稳定性良好。该酶具有较好的金属离子耐受能力，Fe2+、K+、Na+、Mn2+、Ca2+、Mg2+对酶活均有不同程度的激活作用。丝氨酸蛋白酶特异性抑制剂（PMSF）能强烈抑制该酶的酶活性，表明该蛋白酶为丝氨酸碱性蛋白酶。非离子型表面活性剂Tween-20、Tween-80及Triton X-100和阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）对酶活均有较强的抑制作用。该酶具有良好的耐盐性。其米氏常数（Km）为1.11 mg/mL，最大反应速率（Vmax）为91.74 μg/（min·mL），说明该碱性蛋白酶与酪蛋白的亲和力好，特异性强。

Preliminary study of enzymatic characterization of extracellular protease from Bacillus NCB-01

The enzymatic characteristics of extracellular protease secreted by Bacillus NCB-01 in the sediments of Bohai Sea were preliminarily studied. The results showed that the optimum temperature of the protease was 60 ℃ and the optimum pH value was 8.0. The enzyme has good stability in the low temperature environment below 50 ℃ and in the pH value 7.0-9.0. In addition, the protease could be activated by some metal ions such as Fe2+, K+, Na+, Mn2+, Ca2+, Mg2+ and inhibited by serine protease inhibitors (PMSF), suggesting that the protease was an alkaline serine protease. The non-ionic surfactants Tween-80, Tween-20 and Triton X-100 and cationic surfactants hexadecyl trimethyl ammonium bromide (CTAB) had strong inhibitory effects on enzyme activity. The protease exhibited good salt tolerance. Michaelis constant (Km) and the maximum reaction rate (Vmax) were 1.11 mg/ml and 91.74 μg/(min·ml), respectively, suggesting that the alkaline protease had good affinity and high specificity with casein.