Properties of a Metagenome-Derived β-Glucosidase from the Contents of Rabbit Cecum
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概要
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In this study, a previously cloned β-glucosidase gene, umbgl3B, was heterologously expressed in Escherichia coli, and the biochemical properties of the purified enzyme were characterized. The recombinant enzyme was stable over a wide range of pH values (5.0–9.0) and below 30 °C. It displayed optimum enzymatic activity at pH 6.5 at 40 °C, under condition similar to that in the rabbit cecum, suggesting an active role of the native enzyme in vivo. The recombinant β-glucosidase Umbgl3B showed high activity to aryl β-D-glucosides and low activity to cellooligosaccharides, with a polymerization degree of less than 5. The enzyme had no activity toward long cellooligosaccharides or polysaccharides. The aspartic acid residue, D772, of the wild-type Umbgl3B was predicted as a nucleophile. Mutant D772A was constructed. It showed less than 1/10,000 activity of the wild-type enzyme, but had the same properties, suggesting that residue D772 plays a key role in the enzyme’s activity.
- 2009-07-23
著者
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Duan Cheng-jie
Guangxi Key Laboratory Of Subtropical Bioresource Conservation And Utilization The Key Laboratory Of
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Feng Yi
Guangxi Key Laboratory Of Subtropical Bioresource Conservation And Utilization The Key Laboratory Of
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Tang Ji-liang
Guangxi Key Laboratory Of Subtropical Bioresource Conservation And Utilization The Key Laboratory Of
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LIU Li
Guangxi Key Laboratory of Subtropical Bioresource Conservation and Utilization, The Key Laboratory o
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FENG Jia-Xun
Guangxi Key Laboratory of Subtropical Bioresource Conservation and Utilization, The Key Laboratory o
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Feng Jia-xun
Guangxi Key Laboratory Of Subtropical Bioresource Conservation And Utilization The Key Laboratory Of
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Liu Li
Guangxi Key Laboratory Of Subtropical Bioresource Conservation And Utilization The Key Laboratory Of
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Duan Chen-Jie
Guangxi Key Laboratory of Subtropical Bioresource Conservation and Utilization, The Key Laboratory of the Ministry of Education for Microbial and Plant Genetic Engineering and College of Life Science and Technology, Guangxi University