昆虫II家族几丁质酶（ChtII）是含有4-5个催化结构域和4-7个几丁质结合结构域且分子量大于300kD的几丁质降解酶。ChtII存在于蜕皮液中，对昆虫的蜕皮至关重要。但ChtII催化几丁质水解的分子机制目前未知。本项目申请以家蚕BmChtII为研究对象，通过分析其催化结构域的晶体结构以及水解几丁质的酶学特征，将阐明其复杂结构在水解几丁质过程中的作用模式和意义；进一步揭示BmChtII与蜕皮液中其他两种几丁质酶同时存在时协同作用机制。预期成果将对解决目前未知的“昆虫表皮几丁质高效降解机制”这一科学问题具有重要理论意义。

The insect family II chitinase (ChtII) is a complex-structured chitinolytic enzyme with a molecular weight of over 300kD and multi-domains including 4-5 catalytic domains and 4-7 chitin binding domains. It functions in molting fluid and is proved to be essential for insect molting. However, the molecular mechanism of chitin degradation by ChtII is still a mystery. This proposal will focus on ChtII from Bombyx mori. We are going to analyze ChtII's crystal structure and its enzymatic properties, in order to reveal the catalytic mechanism of ChtII during chitin hydrolysis. Further, we will study the synergistic effect of ChtII together with the other two molting fluid chitinases during chitin degradation. The aim of this proposal is to provide clues for revealing the unknown molecular mechanism of insect cuticular chitin degradation during molting.