STUDY ON CHITIN-DEGRADING ENZYMES FROM A MARINE

海洋甲壳素降解酶的研究

基本信息

批准号：
05671851
负责人：
TSUJIBO Hiroshi
金额：
$ 1.02万
依托单位：
OSAKA UNIVERSITY OF PHARMACEUTICAL
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1995
项目状态：
已结题

项目摘要

Chitin, beta- (1,4) polymer of N-acetylglucosamine (GlcNAc), is a major costituent of the cell wall of fungi and the exoskelton of insects and crustaceans. This polymer is second only to cellulose in natural abundance and the annual production is estimated to be approximately 10^9-10^<11> tons. Thus, chitin has attracted the attention of many researchers as a reusable biomass.The purpose of the present investigation is to clarify the chitin-degradation system in a molecular level in a marine bacterium, Alteromonas sp.strain O-7. Recently, it was found that this strain produced five kinds of chitinases (ChiA,B,C,D,E) was three kinds of N-acetylglucosaminidases (GlcNAcaseA,B,C) when the microorganism was grown in a medium containing chitin as a carbon source. Among them, the nucleotide sequences of ChiA,ChiC,GlcNacaseB and GlcNAcaseC genes were determined. Analysis and comparison of the deduced amino acid sequences revealed that ChiA and ChiC were composed of three domain structures. ChiA contained chitin-binding domain at its N-terminus, followed by a glycosyl hydrase family 18 catalytic domain and novel chitin and cellulose-binding domain (CBD). ChiC contained CBD at its N-terminus, followed by fibronectin type-II domain and catalytic domain.We identified two acid residues (Glu and Asp) involved in the catalysis of ChiA.In the case of GlcNAcaseB,like chitinase, Asp-316 and Asp-348 seemed to be essential residues in the active site of the enzyme.At the present time, we are cloning and sequencing the remaining chitinases and GlcNAcaseA genes to clarify the relationship between structure and function, and also studying the real inducer involved in the induction of chitin-degrading enzymes.

金乙酰基葡萄糖（GlcNAC）的几丁质，β-（1,4）聚合物是真菌细胞壁的主要成本，以及昆虫和甲壳类动物的外生。该聚合物仅在自然丰度中仅次于纤维素，估计每年的产量约为10^9-10^<11>吨。因此，几丁质吸引了许多研究人员作为可重复使用的生物质的注意。本研究的目的是在海洋细菌中以分子水平阐明几丁质降解系统，Alteromonas sp.Strain O-7。最近，发现这种菌株产生了五种几丁质酶（Chia，b，c，d，e）是三种N-乙酰葡萄糖氨基酶（Glcnacasea，b，c）碳源。其中，确定了CHIA，CHIA，GLCNACASEB和GLCNACASEC基因的核苷酸序列。对推导的氨基酸序列的分析和比较表明，Chia和Chic由三个域结构组成。 Chia在其N末端包含几丁质结合结构域，其次是糖基水解酶家族18催化结构域以及新颖的几丁质和纤维素结合结构域（CBD）。别致在其N末端包含CBD，然后是纤连蛋白II型结构域和催化结构域。我们确定了CHIA催化的两个酸残基（GLU和ASP）。 ASP-348似乎是酶的活性部位的必不可少的残基。在当前，我们正在克隆和测序其余的几丁质酶和Glcnacasea基因，以阐明结构和功能之间的关系，并研究涉及的实际诱导剂，并研究了涉及的实际诱导剂诱导有丁质降解酶。