江米酒凝乳酶的纯化及凝乳机制初探

江米酒凝乳酶是扣碗酪生产中起关键作用的凝乳因子。文中采用纤维素离子交换柱从江米酒中得到分子质量为36·4ku的单一蛋白酶,其凝乳活力与蛋白酶水解活力的比值从纯化前的3·1提高到16·0。对纯化酶的基本特性研究表明,该酶在30~55℃,pH值3·0~7·0保持比较稳定的酶活性,而与胃蛋白酶、米黑毛霉凝乳酶及牛凝乳酶凝乳过程中的组织状态变化比较,初步认为江米酒凝乳酶的动力学或凝乳机制可能与牛凝乳酶等其他天冬氨酸蛋白酶不完全相同。

Purification and Preliminary Discussion on Coagulation Mechanism of Rennet from Glutinous Rice Wine

The rennet of glutinous rice wine is the primary milk-clotting enzyme used for manufacture of Kou Wanlao. The molecular weight of purified protease from the glutinous rice wine by cellulose anion exchange column was 36.4ku on SDS-PAGE and the ratio of milk-clotting activity to proteolytic activity was enhanced from 3.1 to 16.0. The study on the properties showed that the milk-clotting activity and proteolytic activity were kept stable at the temperature between 30～55℃ and at the pH 3.0～7.0. When compared the change of milk with pepsin and rennet from Mucor miehei and cattle during milk coagulation, the results may indicate the subtle difference in the kinetics or mechanism of the coagulation reaction of rennet from glutinous rice wine.