Structural and Molecular Biology Laboratory, School of Life Sciences and Biotechnology, Kyungpook National University , Daehak-ro 80, Buk-ku, Daegu 702-701, Republic of Korea.
School of Nano-Bioscience and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , Ulsan, 689-798, Republic of Korea.
J Agric Food Chem. 2016 Jul 20;64(28):5662-70. doi: 10.1021/acs.jafc.6b02296. Epub 2016 Jul 8.
Amylomaltase is an essential enzyme in maltose utilization and maltodextrin metabolism, and it has been industrially used for the production of cyclodextrin and modification of starch. We determined the crystal structure of amylomaltase from Corynebacterium glutamicum (CgAM) at a resolution of 1.7 Å. Although CgAM forms a dimer without NaCl, it exists as a monomer in physiological concentration of NaCl. CgAM is composed of N- and C-terminal domains, which can be further divided into two and four subdomains, respectively. It exhibits a unique structural feature at the functionally unknown N-domain and also shows two striking differences at the C-domain compared to other amylomaltases. These differences at extended edge of the substrate-binding site might affect substrate specificity for large cyclodextrin formation. The bis-tris methane and sulfate molecules bound at the substrate-binding site of our current structure mimic the binding of the hydroxyl groups of glucose bound at subsites -1 and -2, respectively.
淀粉麦芽糖酶是麦芽糖利用和麦芽糊精代谢中的一种必需酶，它已被工业用于环糊精的生产和淀粉的修饰。我们解析了来自谷氨酸棒杆菌（Corynebacterium glutamicum）的淀粉麦芽糖酶（CgAM）的晶体结构，分辨率为 1.7 Å。尽管 CgAM 在没有 NaCl 的情况下形成二聚体，但在生理浓度的 NaCl 中它以单体形式存在。CgAM 由 N 端和 C 端结构域组成，它们可以进一步分为两个和四个亚结构域。它在功能未知的 N 结构域表现出独特的结构特征，并且与其他淀粉麦芽糖酶相比，在 C 结构域也显示出两个显著的差异。底物结合位点的扩展边缘的这些差异可能影响形成大的环糊精的底物特异性。当前结构中结合在底物结合位点的双三羟甲基甲烷和硫酸盐分子分别模拟了结合在 -1 和 -2 亚位点的葡萄糖的羟基的结合。
