酶催化魔芋葡甘聚糖的可控降解

魔芋葡甘聚糖 (KGM)是一种来自植物的天然高分子 .它具有优异的可生物降解性和生物相容性 ,并具有许多独特的生理和药理功能 .本实验首先测定了 β 甘露糖酶在不同条件 (温度、pH值、介质 )下的活性 ,发现 β 甘露糖酶在 5 0℃左右 ,pH 9 4附近 ,乙醇含量低于 5 %的水介质中具有较高的活力 ;而在pH 7 0以下 ,或温度低于 3 0℃ ,或加入 2 0 %乙醇的条件下均基本上失活 .在此研究基础上 ,探讨了 β 甘露糖酶催化KGM降解反应的规律 ,通过调节反应条件制备了一系列分子量不同的降解样品 ,并确定了KGM的分子量与特性粘数之间的关系为 :η]=5 0 6× 1 0 - 4M0 754w ,使得酶催化KGM的可控降解成为可能 ,从而为深入研究KGM及其衍生物的结构与性能 ,扩展其应用领域奠定了良好的理论和实验基础

ENZYME-CATALYZED CONTROLLABLE DEGRADATION OF KONJAC GLUCOMANNAN

Konjac glucomannan (KGM) is a natural polymer from a plant. It possesses excellent biodegradability,biocompatibility and many unique physiological and pharmacological functions. In this work the effects of various factors (i.e.,temperatures,pH,medium) on the activity of β-mannanase was firstly studied. The results show thatβ-mannanase possesses high activity in the aqueous medium (pH 9 4) containing enthanol less than 5% (V/V) at about 50℃,and basically lose its activity in the medium with pH lower than 7 0 or containing enthanol more than 20%(V/V),or at temperatures lower than 30℃. Based on these results,the degradation reaction of KGM catalyzed byβ-mannanase and its affecting factors were investigated,and a series of KGM samples with different molecular weights was prepared by adjusting the reaction conditions. Moreover,the intrinsic viscosity (η]) and the weight-average molecular weight (M w) of the degraded KGM products were measured,obtaining the following equation:η]=5 06×10 -4 M 0 754 w. This work makes it possible to realize controllable degradation of KGM by means of an enzyme-catalyzed reaction,thus laying a solid experimental and theoretical foundation for further studying the structure and properties of KGM and its derivatives,and developing new application fields of them.