Cho Chang-Bae, Park Da-Yeon, Lee Soo-Bok
Department of Food and Nutrition, Brain Korea 21 Project, Yonsei University, Seoul 120-749, Republic of Korea.
Department of Food and Nutrition, Brain Korea 21 Project, Yonsei University, Seoul 120-749, Republic of Korea.
Enzyme Microb Technol. 2017 Jan;96:121-126. doi: 10.1016/j.enzmictec.2016.10.006. Epub 2016 Oct 13.
The C-terminal domain of the three-domain-comprising trehalose synthase from Thermus thermophilus was truncated in order to study the effect on the enzyme's activity and substrate specificity. Compared with the wild-type (WT) enzyme, the two truncated enzymes (DM1 and DM2) showed lower maltose- and trehalose-converting activities and a different transglycosylation reaction mechanism. In the mutants, the glucose moiety cleaved from the maltose substrate was released from the enzyme and intercepted by external glucose oxidase, preventing the production of trehalose. The WT enzyme, however, retained the glucose in the active site to effectively produce trehalose. In addition, DM1 synthesized much higher amounts of mannose-containing disaccharide trehalose analog (Man-TA) than did the WT and DM2. The results suggest that the C-terminal domain in the WT enzyme is important for retaining the glucose moiety within the active site. The mutant enzymes could be used to produce Man-TA, a postulated inhibitor of gut disaccharidases.
为了研究对嗜热栖热菌三结构域海藻糖合酶C末端结构域对酶活性和底物特异性的影响，对其进行了截短。与野生型（WT）酶相比，两种截短酶（DM1和DM2）表现出较低的麦芽糖和海藻糖转化活性以及不同的转糖基化反应机制。在突变体中，从麦芽糖底物上裂解下来的葡萄糖部分从酶中释放出来，并被外部葡萄糖氧化酶截获，从而阻止了海藻糖的产生。然而，WT酶将葡萄糖保留在活性位点以有效产生海藻糖。此外，DM1合成的含甘露糖的二糖海藻糖类似物（Man-TA）比WT和DM2多得多。结果表明，WT酶中的C末端结构域对于将葡萄糖部分保留在活性位点内很重要。突变酶可用于生产Man-TA，一种假定的肠道二糖酶抑制剂。
