中文摘要：

凝乳酶是一种最早在未断奶的小牛胃中发现的天门冬氨酸蛋白酶，可专一地切割乳中κ-酪蛋白R Phe10^5—Met10^6之间的肽键，破坏酪蛋白胶束使牛奶凝结，凝乳酶的凝乳能力及蛋白水解能力使其成为干酪生产中形成质构和特殊风味的关键性酶，被广泛地应用于奶酪和酸奶的制作。本文以牛凝乳酶为例介绍了凝乳酶的结构、理化特性和凝乳机理．综述了凝乳酶主要来源以及不同来源凝乳酶之间酶性质差异，旨在为凝乳酶研究提供些许参考。

英文摘要：

Chymosin （rennin; EC 3.4.23.4） belongs to a aspartic proteinase family which was found in unweaned bovine stomachs at first. It can specifically cleave the K-casein at the Phel05-Met106 peptide bond to broke the casein micelles causing milk-clotting. In cheese produc- tion,chymosin plays an important role as the key enzyme in milk-clotting and processing of texture and flavour. The structure, physicochemical characteristics and milk coagulation mechanism of bovine chymosin were reviewed in this paper. Otherwise, the source of chymosin and the diversity from different sources were discussed.