van Bueren Alicia Lammerts, Otani Suzie, Friis Esben P, Wilson Keith S, Davies Gideon J
Structural Biology Laboratory, Department of Chemistry, University of York, York, England.
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2012 Feb 1;68(Pt 2):141-4. doi: 10.1107/S1744309111049608. Epub 2012 Jan 25.
Thermostable enzymes employ various structural features dictated at the amino-acid sequence level that allow them to maintain their integrity at higher temperatures. Many hypotheses as to the nature of thermal stability have been proposed, including optimized core hydrophobicity and an increase in charged surface residues to enhance polar solvent interactions for solubility. Here, the three-dimensional structure of the family GH11 xylanase from the moderate thermophile Thermobifida fusca in its trapped covalent glycosyl-enzyme intermediate complex is presented. Interactions with the bound ligand show fewer direct hydrogen bonds from ligand to protein than observed in previous complexes from other species and imply that binding of the xylan substrate involves several water-mediated hydrogen bonds.
嗜热酶利用氨基酸序列水平决定的各种结构特征，使其能够在较高温度下保持完整性。关于热稳定性的本质，已经提出了许多假说，包括优化核心疏水性以及增加带电荷的表面残基以增强极性溶剂相互作用来提高溶解度。在此，展示了来自嗜温嗜热栖热放线菌的GH11木聚糖酶家族在其捕获的共价糖基 - 酶中间体复合物中的三维结构。与结合配体的相互作用显示，与其他物种先前复合物中观察到的相比，配体与蛋白质之间的直接氢键更少，这意味着木聚糖底物的结合涉及几个水介导的氢键。
