Zhao Hua, Baker Gary A, Holmes Shaletha
Chemistry Program, Savannah State University, Savannah, GA 31404, USA.
J Mol Catal B Enzym. 2011 Nov 1;72(3-4):163-167. doi: 10.1016/j.molcatb.2011.05.015.
Deep eutectic solvents (DESs) consisting of mixtures of a choline salt (chloride or acetate form) and glycerol are prepared as easily accessible, biodegradable, and inexpensive alternatives to conventional aprotic cation-anion paired ionic liquids. These DES systems display excellent fluidity coupled with thermal stability to nearly 200 °C. In this work, the transesterification activities of cross-linked proteases (subtilisin and α-chymotrypsin), immobilized on chitosan, were individually examined in these novel DESs. In the 1:2 molar ratio mixture of choline chloride/glycerol containing 3% (v/v) water, cross-linked subtilisin exhibited an excellent activity (2.9 μmo l min(-1) g(-1)) in conjunction with a selectivity of 98% in the transesterification reaction of N-acetyl-L-phenylalanine ethyl ester with 1-propanol. These highly encouraging results advocate more extensive exploration of DESs in protease-mediated biotransformations of additional polar substrates and use of DESs in biocatalysis more generally.
由胆碱盐（氯化物或醋酸盐形式）和甘油的混合物组成的深共熔溶剂（DESs）被制备出来，作为传统非质子阳离子-阴离子配对离子液体易于获取、可生物降解且价格低廉的替代品。这些DES体系表现出优异的流动性以及近200℃的热稳定性。在这项工作中，固定在壳聚糖上的交联蛋白酶（枯草杆菌蛋白酶和α-胰凝乳蛋白酶）的酯交换活性在这些新型DES中分别进行了研究。在含有3%（v/v）水的氯化胆碱/甘油1:2摩尔比混合物中，交联枯草杆菌蛋白酶在N-乙酰-L-苯丙氨酸乙酯与1-丙醇的酯交换反应中表现出优异的活性（2.9 μmol min(-1) g(-1)）以及98%的选择性。这些非常令人鼓舞的结果提倡更广泛地探索DES在蛋白酶介导的其他极性底物生物转化中的应用，以及更普遍地将DES用于生物催化。
