肠杆菌酸性脲酶的提取及基本特性

采用超声破碎和乙醇分级沉淀的方法,对肠杆菌所产酸性脲酶的提取进行了研究,超声破碎最佳条件为:缓冲液pH6.0,湿菌体(质量)︰缓冲液(体积)=1∶5,功率300W,处理时间10min,乙醇分级较好浓度范围为30%～50%;研究乙醇分级后粗酶的基本特性,结果表明,粗酶液的最适温度75℃,温度稳定范围75℃以下,最适pH5.5,pH稳定范围为pH4.0～ pH6.5;粗酶在黄酒中的应用结果表明,在30℃下添加量为0.05U/mL时,24h后尿素去除率可达70%以上。

The extraction of an acid urease from enterobacteria was studied by the methods of ultrasonication and ethanol fractional precipitation. The optimal ultrasonication conditions are： the pH of the buffer solution was pH6.0; the ratio of the wet cell （weight） to the buffer solution （volume） was 1：5 （g/mL）; the ultrasonication power was 300W; the treatment time was 10min. The preferable concentration range of ethanol fractional precipitation was 30%-50%. The characterization of this crude acid urease was carried out. The optimal temperature and the optimal pH of the crude acid urease was 75℃ and 5,5 respectively. The enzyme was stable below 75℃ or within a pH range of 4.0-6.5. The urea decomposition rate was more than 70% in Chinese rice-wine within 24h after addition of 0.05U/mL this urease at 30℃.