Characterization of a Thermophilic l-Rhamnose Isomerase from Thermoanaerobacterium saccharolyticum NTOU1
详细信息 查看全文
- 作者：Chia-Jui Lin ; Wen-Chi Tseng ; Tien-Hsiang Lin ; Shiu-Mei Liu ; Wen-Shyong Tzou ; Tsuei-Yun Fang
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2010
- 出版时间：October 13, 2010
- 年：2010
- 卷：58
- 期：19
- 页码：10431-10436
- 全文大小：874K
- 年卷期：v.58,no.19(October 13, 2010)
- ISSN：1520-5118
文摘
l-Rhamnose isomerase (EC 5.3.1.14, l-RhI) catalyzes the reversible aldose−ketose isomerization between l-rhamnose and l-rhamnulose. In this study, the l-rhi gene encoding l-RhI was PCR-cloned from Thermoanaerobacterium saccharolyticum NTOU1 and then expressed in Escherichia coli. A high yield of the active l-RhI, 9780 U/g of wet cells, was obtained in the presence of 0.2 mM IPTG induction. l-RhI was purified sequentially using heat treatment, nucleic acid precipitation, and anion-exchange chromatography. The purified l-RhI showed an apparent optimal pH of 7 and an optimal temperature at 75 °C. The enzyme was stable at pH values ranging from 5 to 9, and the activity was fully retained after a 2 h incubation at 40−70 °C. l-RhI from T. saccharolyticum NTOU1 is the most thermostable l-RhI to date, and it has a high specific activity (163 U/mg) and an acceptable purity after heat treatment, suggesting that this enzyme has the potential to be used in rare sugar production.