咪唑类离子液体在纤维素酶降解纤维素体系中的作用

以1-乙基-3-甲基咪唑磷酸二乙酯(Emim]DEP)、1-乙基-3-甲基咪唑醋酸(Emim]Ac)为研究对象, 考察两种离子液体(IL)对酶法降解纤维素过程的影响。采用超声辅助离子液体溶解纤维素, Emim]DEP和Emim]Ac分别使纤维素的结晶度降为53.6%和62.3%。在纤维素酶降解再生纤维素的过程中, 当IL的加入量小于2.0%时, 对酶解过程起促进作用, 其中加入量为0.5%时, 促进作用最强, 酶解率分别提高了11.4%和17.5%。在最优条件下(加入0.5%IL), 测量纤维素酶系中各个酶的酶活, 结果表明离子液体对β-葡萄糖苷酶起到了明显的促进作用, 分别使该酶酶活提高了120%和87%。离子液体降低了纤维二糖对葡聚糖外切酶的抑制作用, 提高了酶解效率。

Function of imidazolium-based ionic liquids in system of enzymatic degradation of cellulose

Taking 1-ethyl-3-methylimidazolium diethyl phosphate (Emim]DEP) and 1-ethyl-3-methylimidazolium acetate (Emim]Ac) as research targets, the influence of the two ionic liquids (IL) on the process of enzymatic degradation of cellulose was investigated. By using ultrasound to assist ionic liquids in dissolving cellulose, Emim]DEP and Emim]Ac made the crystallinity of cellulose decrease to 53.6% and 62.3% respectively. In the process of enzymatic degradation of regenerated cellulose, when the dosage of IL was less than 2.0%, IL acted as promoter, and when the dosage of IL was 0.5%, the promoting effect of IL was the strongest. Enzymatic hydrolysis rate increased by 11.4% and 17.5% respectively. Under the optimal conditions (add in 0.5% IL), the enzyme activities of every enzyme in the cellulose system were measured. Ionic liquids had an obvious promoting effect on β-glucosidase, increasing enzyme activity by 120% and 87% respectively. Ionic liquids reduced inhibition of exoglucanase by cellubiose, and improved efficiency of enzymatic degradation of cellulose.