Hanazono Yuya, Takeda Kazuki, Niwa Satomi, Hibi Masahito, Takahashi Naoya, Kanai Tamotsu, Atomi Haruyuki, Miki Kunio
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Japan.
Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Japan.
FEBS Lett. 2016 Jan;590(2):298-304. doi: 10.1002/1873-3468.12055. Epub 2016 Jan 20.
Chitinase from T. kodakarensis (TkChiA) catalyzes the hydrolysis of chitin. The enzyme consists of two catalytic and three binding domains (ChBD1, ChBD2 and ChBD3). ChBD2 and ChBD3 can bind to not only chitin but also cellulose. In both domains, the intervals of the side chains of the three tryptophan residues, which are located on the molecular surface, correspond to twice the length of the lattice of the chitin. A binding model with crystalline chitin implies that the tryptophan residues and a glutamate residue interact with the hexose ring by CH-π interactions and the amide group by a hydrogen bond, respectively.
来自嗜碱栖热菌（T. kodakarensis）的几丁质酶（TkChiA）催化几丁质的水解。该酶由两个催化结构域和三个结合结构域（几丁质结合结构域1、几丁质结合结构域2和几丁质结合结构域3）组成。几丁质结合结构域2和几丁质结合结构域3不仅可以结合几丁质，还可以结合纤维素。在这两个结构域中，位于分子表面的三个色氨酸残基侧链的间隔对应于几丁质晶格长度的两倍。与结晶几丁质的结合模型表明，色氨酸残基和一个谷氨酸残基分别通过CH-π相互作用与己糖环相互作用，并通过氢键与酰胺基团相互作用。
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