Tanaka Megumi, Umemoto Yoshiaki, Okamura Hidenori, Nakano Daiichirou, Tamaru Yutaka, Araki Toshiyoshi
Graduate School of Bioresources, Mie University.
Biosci Biotechnol Biochem. 2009 Jan;73(1):109-16. doi: 10.1271/bbb.80521. Epub 2009 Jan 7.
The beta-1,4-mannanase 5C gene (man5C) of Vibrio sp. strain MA-138 was cloned and expressed in Escherichia coli. The man5C gene consisted of 2,010 bp nucleotides encoding a protein of 669 amino acids with a predicted molecular weight of 76,309. beta-1,4-Mannanase (Man5C) is a modular enzyme composed of a catalytic module belonging to glycoside hydrolase family 5, a linker region, and a putative carbohydrate-binding module (CBM) belonging to family 27. Recombinant Man5C exhibited maximal activity at 50 degrees C at pH 7.0, and it had a K(m) of 0.6 mg ml(-1) and a V(max) of 556.2 micromol min(-1) mumol(-1) for glucomannan. Binding studies revealed that the C-terminal putative CBM27 had the ability to bind soluble beta-mannans and contributed to increasing the rate of depolymerization by binding to the polymeric substrate. Man5C of Vibrio sp. MA-138 is the first non-extremophile enzyme to be identified as a beta-mannanase possessing CBM27.
克隆了弧菌属MA-138菌株的β-1,4-甘露聚糖酶5C基因（man5C）并在大肠杆菌中进行表达。man5C基因由2010个碱基对组成，编码一个含有669个氨基酸的蛋白质，预测分子量为76309。β-1,4-甘露聚糖酶（Man5C）是一种模块化酶，由属于糖苷水解酶家族5的催化模块、一个连接区和一个属于27家族的假定碳水化合物结合模块（CBM）组成。重组Man5C在50℃、pH 7.0时表现出最大活性，对葡甘露聚糖的K(m)为0.6 mg ml(-1)，V(max)为556.2 μmol min(-1) μmol(-1)。结合研究表明，C端假定的CBM27具有结合可溶性β-甘露聚糖的能力，并通过与聚合物底物结合有助于提高解聚速率。弧菌属MA-138的Man5C是首个被鉴定为具有CBM27的β-甘露聚糖酶的非嗜极酶。
