异构酶
嗜热脂肪地芽孢杆菌
阿拉伯糖
生物化学
酶动力学
酶
半乳糖
大肠杆菌
化学
生物
基因
活动站点
嗜热菌
木糖
发酵
作者
HyeonJin Kim,J.‐H. Kim,Hyo Jung Oh,Deok‐Kun Oh
标识
DOI:10.1111/j.1365-2672.2006.02975.x
摘要
Characterization of a mutated Geobacillus stearothermophilus L-arabinose isomerase used to increase the production rate of D-tagatose.A mutated gene was obtained by an error-prone polymerase chain reaction using L-arabinose isomerase gene from G. stearothermophilus as a template and the gene was expressed in Escherichia coli. The expressed mutated L-arabinose isomerase exhibited the change of three amino acids (Met322-->Val, Ser393-->Thr, and Val408-->Ala), compared with the wild-type enzyme and was then purified to homogeneity. The mutated enzyme had a maximum galactose isomerization activity at pH 8.0, 65 degrees C, and 1.0 mM Co2+, while the wild-type enzyme had a maximum activity at pH 8.0, 60 degrees C, and 1.0-mM Mn2+. The mutated L-arabinose isomerase exhibited increases in D-galactose isomerization activity, optimum temperature, catalytic efficiency (kcat/Km) for D-galactose, and the production rate of D-tagatose from D-galactose.The mutated L-arabinose isomerase from G. stearothermophilus is valuable for the commercial production of D-tagatose.This work contributes knowledge on the characterization of a mutated L-arabinose isomerase, and allows an increased production rate for D-tagatose from D-galactose using the mutated enzyme.
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