玫瑰考克氏菌(Kocuria rosea)KDF3胞外蛋白酶KRP3酶学性质与水解大豆蛋白产物研究

Research on the Properties of an Extracellular Protease KRP3 from Kocuria rosea KDF3 and Its Soy Protein Hydrolysates

从我国传统细菌发酵腐乳中筛选出一株对大豆蛋白具有良好水解活性的玫瑰考克氏菌（犓狅犮狌狉犻犪狉狅狊犲犪）KDF3。在研究了该菌株胞外蛋白酶KRP3的酶学性质基础上，利用氨基酸检测技术分析了该酶水解大豆蛋白产生的氨基酸指纹图谱。实验结果表明，该酶的最适反应温度和pH 分别为50℃和8．0，在20～40℃和pH 5．0～7．0具有良好的稳定性，60℃保温30 min即可灭活；对10％的乙醇和11％的NaCl均有很好的耐受性；Ca2＋和Mn2＋对该酶激活作用显著。由该酶水解大豆蛋白产生的氨基酸图谱可知，总游离氨基酸、必需氨基酸和风味氨基酸的含量均明显增加。由以上结果可知，该酶在酶法促熟和酶法发酵腐乳领域具有潜在的应用价值。

Kocuria rosea KDF3 with high hydrolyzed active to soybean protein is selected from tradi-tional bacterium fermented bean curd.Amino acid analysis techniques are used to examine the amino acid fingerprint spectrum of soy protein,which is hydrolyzed by extracellular protease KRP3 on the basis of enzymatic properties.The KRP3 protease exhibits maximal activity at pH 8.0 and 50 ℃;it is stable at pH 5.0~7.0 and 20~40 ℃;it is inactivate under 60 ℃ for 30 min and shows high stability in the presence of 10% ethanol and 11% NaCl.The activity of KRP3 is enhanced by the presence of Ca2＋ and Mn2＋ ions.The amino acid pattern shows that the content of total free amino acids,essential amino acids and flavor amino acids is significantly increased.The results show that the KRP3 has potential application value in the field of enzymatic fermented bean curd.