长野芽孢杆菌普鲁兰酶的同源建模及三维结构分析

摘要

普鲁兰酶(Pullulanase)是脱支酶,因其能水解葡聚糖的α-1,6-糖苷键而有不同的工业应用潜力.本研究通过同源建模和分子对接的方法对长野芽孢杆菌(Bacillus naganoensis) 普鲁兰酶进行建模及其三维结构分析,表明该酶由CBM41-X45a-X25-X45b-CBM48-GH13_14多结构域组成,酶蛋白中心形成其催化区,催化区的Asp619、Glu648和 Asp733三个残基构成酶的催化三联体.同时,通过柔性对接研究了酶与底物分子相互作用的关系,并预测构成酶的活性中心相关氨基酸残基,为进一步改良酶的特性提供重要的理论依据.%Pullulanase is a debranching enzyme that specifically hydrolyzes the α-1,6-glycosidic bonds in complex carbohydrates and has great potential in various industries.Here, we investigate the structural characteristics of the Bacillus naganoensis pullulanase (BnPulB) by homology modeling and molecule docking.Results show that the BnPulB structure comprises the CBM41-X45a-X25-X45b-CBM48-GH13_14 multi-domain architecture and the central region of the protein forms the catalytic domain, and the highly conserved Asp619, Glu648, and Asp733 residues are identified to be catalytic triad.In addition, flexible docking studies of the enzyme-substrate system show the interactions between BnPulB and its substrate, maltotriose, and some conserved residues locate in the active centre that participate in ligand binding site are predicted.This study may provide important information for the design of new pullulanase with novel properties.