酶法转化 D-半乳糖为 D-塔格糖：戊糖片球菌 PC-5 中 L-阿拉伯糖异构酶的克隆、过表达及特性研究。
Enzymatic conversion of D-galactose to D-tagatose: cloning, overexpression and characterization of L-arabinose isomerase from Pediococcus pentosaceus PC-5.
机构信息
National Engineering Laboratory for Industrial Enzymes, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China.
Shanxi Tianjiao Biological Co., Ltd, Shanxin 030006, China.
出版信息
Microbiol Res. 2014 Feb-Mar;169(2-3):171-8. doi: 10.1016/j.micres.2013.07.001. Epub 2013 Aug 12.
The gene encoding L-arabinose isomerase from food-grade strain Pediococcus pentosaceus PC-5 was cloned and overexpressed in Escherichia coli. The recombinant protein was purified and characterized. It was optimally active at 50 °C and pH 6.0. Furthermore, this enzyme exhibited a weak requirement for metallic ions for its maximal activity evaluated at 0.6 mM Mn(2+) or 0.8 mM Co(2+). Interestingly, this enzyme was distinguished from other L-AIs, it could not use L-arabinose as its substrate. In addition, a three-dimensional structure of L-AI was built by homology modeling and L-arabinose and D-galactose were docked into the active site pocket of PPAI model to explain the interaction between L-AI and its substrate. The purified P. pentosaceus PC-5 L-AI converted D-galactose into D-tagatose with a high conversion rate of 52% after 24 h at 50 °C, suggesting its excellent potential in D-tagatose production.
从食品级戊糖片球菌 PC-5 中克隆并在大肠杆菌中过表达了编码 L-阿拉伯糖异构酶的基因。对重组蛋白进行了纯化和特性分析。该酶在 50°C 和 pH6.0 时活性最佳。此外，该酶对金属离子的活性要求较弱，在 0.6 mM Mn(2+)或 0.8 mM Co(2+)时活性最高。有趣的是，与其他 L-AIs 不同，该酶不能将 L-阿拉伯糖作为其底物。此外，通过同源建模构建了 L-AI 的三维结构，并将 L-阿拉伯糖和 D-半乳糖对接入 PPAI 模型的活性口袋中，以解释 L-AI 与其底物之间的相互作用。纯化的戊糖片球菌 PC-5 L-AI 在 50°C 下反应 24 小时后，将 D-半乳糖转化为 D-塔格糖，转化率高达 52%，表明其在 D-塔格糖生产中具有巨大的应用潜力。
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