Studies on Novel Syntheses of Useful Carbohydrates by Enzyme Hybrid

本项目涉及通过几丁质分解酶p-Nitrophenyl penta-N-acetyl-beta-chitopentaoside酶促合成有用的几丁质寡聚体，其可用作溶菌酶测定的底物，通过将四-N-乙酰基-壳聚糖四糖残基转移到对硝基苯基2-乙酰氨基-2-脱氧-β-D-在含有高浓度DMSO的水溶液中使用溶菌酶制备吡喃葡萄糖苷。此外，里氏木霉几丁质酶催化转糖基化反应，从四-N-乙酰基-壳四糖作为底物的六-N-乙酰基-壳六糖。溶菌酶转糖基化反应比几丁质酶反应更方便地从二-N-乙酰基-壳二糖制备六-N-乙酰基-壳六糖和七-N-乙酰基-壳七糖。改性后的溶菌酶比原溶菌酶具有更好的温度稳定性和耐有机溶剂性。

This project is concerned with the enzymatic syntheses of useful chitinoligo- saccharides by chitinolytic enzymes p-Nitrophenyl penta-N-acetyl-beta-chitopentaoside, which is available as a substrate for a lysozyme assay, was efficiently synthesized by transfer of the tetra-N-acetyl-chitotetraosyl residue to the 4-position of p- nitrophenyl 2-acetamido-2-deoxy-beta-D-glucopyranoside using lysozyme in an aqueous solution containing DMSO in a high concentration. Also, a chitinase from Trichoderma reesei catalyzed a transglycosylation reaction from tetra-N-acetyl-chitotetraose as a substrate to hexa-N-acetyl-chitohexaose. The transglycosylation by lysozyme furthermore afforded a more convenient way of preparing hexa-N-acetyl-chitohexaose and hepta-N-acetyl-chitoheptaose from di-N-acetyl-chitobiose than the chitinase reaction.Enzyme hybrid was prepared by shiff-amino reduction of hen egg-white lysozyme with lactose. The modified lysozyme gained more temperature stability and resistance to organic solvent than the native one.