谷氨酸功能胶束温和催化水解甲基-β-D-纤维二糖苷

合成了一种含有谷氨酸残基的长链烷基表面活性剂N^α-十二烷基-L-谷氨酸. 研究了表面活性剂所形成的胶束体系在较温和条件下催化纤维素模型物甲基-β-D-纤维二糖苷(MCB)水解的反应. 研究表明此功能胶束对MCB水解为葡萄糖的反应在较低的温度(90℃)下就表现出明显的催化作用, 在pH 5.0附近具有最佳的催化水解效果.根据胶束催化的相分离模型获得MCB水解的一级反应速率常数(km).研究了胶束与组氨酸(His)或谷氨酸(Glu)所组成的复配体系对MCB的催化水解作用. 结果表明: 氨基酸小分子的加入极大地促进了水解反应的进行, 而胶束与氨基酸在1:1的摩尔浓度配比时催化效果最好. 温度对水解反应速率以及副产物的产生有明显的影响. 在130℃, pH 5.0的水溶液中, 胶束与谷氨酸的复配体系催化MCB水解反应1.5 h后的葡萄糖收率可达到36.6%. 本文也对此催化体系催化MCB水解反应动力学进行了研究, 获得了催化反应的表观一级速率常数(k_obsd), 计算得到催化水解反应生成葡萄糖的活化能(E_a)为97.18 kJ·mol^-1.

Hydrolysis of Methyl-β-D-cellobioside Catalyzed by Functional Micelles with Glutamic Acid under Mild Conditions

Asurfactant with long alkyl chains and glutamic acid, N^α-dodecyl-L-glutamic acid, was synthesized. Micelles of this surfactant were used to catalyze the hydrolysis of methyl-β-D-cellobioside (MCB), a model substrate of cellulose, under mild conditions. The results indicate that the functional micelle displayed effective catalytic activity for the hydrolysis of MCB to glucose at low temperature (90℃) and an optimal pH of 5.0. The first-order reaction rate constant (k_m) of MCB hydrolysis catalyzed by the synthesized micelles was calculated based on the phase separation model of micellar catalysis. The hydrolysis of MCB catalyzed by the cooperative systems of micelles with glutamic acid (Glu) or histidine (His) was also investigated. The addition of amino acids promoted the hydrolysis of MCB, and the maximumcatalytic efficiency was reached at a molar concentration ratio of micelles to amino acids of 1:1. Temperature considerably influenced the reaction rate and product of MCB hydrolysis. The yield of glucose from MCB hydrolysis catalyzed by the cooperative system of micelles with Glu reached more than 36.6%after 1.5 h at 130℃. The kinetics of this reaction was studied; the apparent first-order rate constants (k_obsd) were obtained and the activation energy (E_a) calculated for the formation of glucose was 97.18 kJ·mol^-1.