非水相中酶催化葡甘聚糖的酯交换反应

探索了生物催化反应制备酯化葡甘聚糖(KGM)衍生物的可能性,并构建了酶催化天然高分子改性的新模式。利用KGM与乙酸乙烯酯在无溶剂体系中的酯交换反应,对8种脂肪酶和5种蛋白酶的催化能力进行了初步评价,并考察了以固定化脂肪酶N ovozym 435作生物催化剂时,不同的非水介质对该反应的影响。结果表明:在本文条件下,这些酶对该反应均具有一定的催化作用;有机溶剂二甲基乙酰胺(DMA c)、甲苯(T o luene)和异辛烷(IOCT)以及其他非水相有机介质,如离子液体N-甲基-咪唑四氟硼酸盐HM im] BF4]-和丁二酸二辛基磺酸钠(AOT)/异辛烷反相胶束体系,均有利于脂肪酶N ovozym 435催化的KGM与乙酸乙烯酯的酯交换反应。

Enzyme-Catalyzed Transesterification of Konjac Glucomannan in Non-aqueous Media

This work aims at exploring the possibility of preparing for esterified konjac glucomannan(KGM) derivatives via a biocatalyzed reaction and establishing a new method for the enzymatic modification of a natural polymers.In order to select appropriate biocatalysts,the catalytic ability of 8 lipases and 5 proteinases were primarily evaluated by means of the transesterification of KGM with vinyl acetate in a solvent-free system.The effect of non-aqueous reaction media on the transesterification of KGM was investigated with Novozym 435 as a biocatalyst.The results indicate that the enzymes used in the experiments possess catalytic activity for the reaction to a certain extent under the adopted conditions,and these organic solvents,dimethyl acetamide(DMAC),toluene and isooctane(IOCT),as well as the other non-aqueous organic media such as ionic liquid HMim]~ ~-and a reverse micelle system AOT/IOCT,are all favorable for the Novozym 435-catalyzed transesterification of KGM with vinyl acetate.