支链淀粉水解酶水解支链淀粉的特异氨基酸分析

【目的】通过对具有支链淀粉水解能力的环糊精水解酶的结构进行分析,探寻决定酶与支链淀粉水解相关的关键氨基酸残基。【方法】对底物特异性发生改变的环糊精水解酶cds1-3进行功能鉴定,并利用分子模拟方法对其底物作用特异氨基酸序列和空间结构进行分析。【结果】环糊精水解酶cds1-3具有特殊的底物作用方式,它水解支链淀粉的能力强于水解环糊精。cds1-3和ThMA的蛋白质序列只有30个氨基酸的差异,主要位于远离底物结合区域的蛋白质中段,与环糊精水解酶的底物通道聚集位置相近。【结论】环糊精水解酶cds1-3的功能鉴定及对其关键氨基酸进行序列和空间结构分析,为揭示大分子底物,特别是支链淀粉底物的水解方式提供新的切入点。

Analysis of the Key Amino Acid of Amylopectin Hydrolase on Amylopectin Hydrolysis

Objective] Exploring the key amino acid of amylopectin hydrolyzed enzyme, which have the ability of hydrolysis of huge substrate, is a possible way toward this problem.Methods] A substrate-specificity mutant of cyclodextrin hydrolase was screened out from an environmental metagenomic library.Molecular simulation technique was applied to analyze the special amino acids related with substrate hydrolysis.Results] Cyclodextrinhydrolase cds 1-3 showed a special mode of substrate hydrolytic action.The best substrate was amylopectin instead of cyclodextrin.This is different with other known cyclodextrin hydrolazed enzymes.Conclusion] Cyclodextrinhydrolasecds 1-3 is a special cyclodextrin enzyme. The sequence and spatial structure analysis of its key amino acids may provide a good basis for hydrolysis of amylopectin.