源于Streptomyces sp. L10904的G/11家族木聚糖酶诱导特异产物生成分子机制研究

我国每年产生大量富含木聚糖的半纤维素类农业废弃物，其资源再生利用率极低。利用酶法制取高附加值低聚木糖是其增值利用有效途径，经济效益和环保意义巨大。目前，酶法生产低聚木糖的功能性成分产率低，后期提纯复杂，成本高，难以实现大规模生产。解决这一难题的关键是阐明酶水解底物如何趋向生成不同聚合度特异性产物的分子机制，尤其需明确酶与底物的结合方式及途径。研究以酶分子关键特定结合位点为突破口来解析木聚糖酶水解底物生成特异性产物的分子机制。采用酶蛋白同源建模、分子对接等手段初步锁定与产物生成相关的底物结合位点，进一步解析不同结合方式、结合位点数量及侧链结合趋向性导致的酶选择催化生成不同特异性产物的分子机制。在此基础上对关键结合位点进行突变重构，对产物生成分子机制验证。探讨酶催化特异性产物生成分子机制这一科学问题完善了酶分子催化理论，为有效利用农业废弃物，减轻环境污染，实现工业化制备高纯低聚木糖奠定理论基。

A large number of hemicellulosic agricultural waste rich in xylan has been produced in China each year and its recycling rate is very low. It is the effective value-added way to hydrolyze hemicelluloses waste using enzyme, which has the great economic and environmental significance. The yield of functional components in xylooligosaccharides are very low and latter purification process are complex, high cost, difficult to achieve large scale production so far. To clarify the molecular mechanism of how specific products in different degree of polymerization formed by enzymatic hydrolysis, especially the binding mode and way of enzyme-substrate, is the key to solve this problem. In this study, the molecular mechanism of the key substrate binding site in enzyme molecule take as the breakthrough point for analyze the molecular mechanism of specific products. Using the protein homology modeling and molecular docking method to preliminary determinate the binding site. Furthermore different binding modes, binding sites and tendency of side chain binding are analyzed to elucidate the molecular mechanism of specific produces. Basis on this, the key binding sites are reconstructed with mutation to verify the molecular mechanism of specific produces. The scientific problem for molecular mechanism of specific products generated has been studied to improve basic molecular mechanism of xylanase catalysis, which increase the effective use of agricultural waste, reduce environmental pollution and lay a theoretical foundation for realizing the industrialized preparation of the high purity xylooligosaccharides.