摘要
葡甘聚糖(KGM)是一种具有优异的生物降解性、生物相容性、独特的生理和药理功能的天然聚多糖。通过环境友好的、高选择性的酶催化转酯化反应引入疏水基团可以制备葡甘聚糖的酯化衍生物,从而拓宽其应用领域。本研究探讨了在非水介质中以脂肪酶Novozym 435、Lipozym RMIM、Lipozym TLIM和Lipase TypeⅦ催化KGM和乙酸乙烯酯的转酯化反应,并且考察了相关因素对转酯化反应的影响。实验结果表明:在非水介质N,N-二甲基乙酰胺、甲苯和异辛烷中,脂肪酶Novozym 435可以较好的催化乙酸乙烯酯和KGM发生转酯化反应。以Novozym 435为催化剂、以异辛烷为反应介质,当底物浓度[S]=30(mg/mL)、酶用量[E]/[S]=0.30(wt/wt)、酰基供体乙酸乙烯酯用量[Acyl]/[OH]=3.0(mol/mol)、50℃、反应72 h的条件下,酯化KGM的取代度(DS)可达到0.49。
Konjac Glucomannan （KGM） is a natural polymer from a plant. It possesses excellent biodegradability,biocompatibility and many tmique physiological functions. KGM can be modified by environmentally friendly and selective enzyme-catalyzed transesteriflcation to form the esterified derivatives of KGM and then its applications will be extended. In this work, the enzyme-catalyzed transesterification of KGM in non-aqueous media by using different lipases such as Novozym 435, Lipozym RMIM,Lipozym TLIM and Lipase TypeⅦ as a catalyst,respectively,was studied,and the effects of each factor on the transesteritication were also investigated. The experimental results indicate that Novozym 435 exhibits higher activity than other three lipases for the transesterification of KGM with vinyl acetate in non-aqueous media iso-octane, toluene and N, N-dimethyl acetamide.In the reaction system using iso-octane as the reaction medium where the substrate concentration is 30 mg/mL, the weight ratio of Novozym 435 to the sbustrate 0.3 and the molar ratio of vinyl acetate to the hydroxyl group on the macromolecular chain of the substrate 3.0,the esterified KGM sample prepared at 50 ℃ for 72 hours can possess as high degree of substitution （ DS ） as 0.49.
出处
《天然产物研究与开发》
CAS
CSCD
2006年第2期198-202,共5页
Natural Product Research and Development
基金
广州市科技计划-应用基础研究项目(2003J1-C0191)
广东省自然科学基金项目(04020031)
关键词
非水介质
脂肪酶
葡甘聚糖
乙酸乙烯酯
转酯化反应
Non-aqueous media
lipase
konjac glucomannan
vinyl acetate
transesterification
