Design of environmentally friendly ionic liquid aqueous two-phase systems for the efficient and high activity extraction of proteins
作者:Zhiyong Li、Xinxin Liu、Yuanchao Pei、Jianji Wang、Mingyuan He
DOI:10.1039/c2gc35890e
日期:——
Ionic liquids (ILs) have numerous applications in industrial processes as a benign alternative to conventional volatile organic solvents. However, many of them are toxic to organisms and are poorly biodegradable. In this work, a series of environmentally friendly cholinium ILs have been designed and synthesized. It was found that these ILs could form aqueous two-phase systems (ATPSs) with polypropylene glycol 400 (PPG400) which is thermo-sensitive, non-toxic and biodegradable. In order to understand the phase formation processes and possible application of these ATPSs for extraction/separation of proteins, the binodal curves and tie lines of these ATPSs were measured at 25 °C, and the effects of anionic structure of the ionic liquids, nature of the proteins and difference in the concentration of top- and bottom-phases on the partitioning behavior of some typical proteins were investigated systematically. It was shown that bovine serum albumin (BSA), trypsin, papain and lysozyme could be enriched effectively into the ionic liquid-rich phase of the ATPSs, and single-step extraction efficiency could be as high as 86.4–99.9% under the optimized conditions. Furthermore, enzyme activity of the native trypsin in water and in aqueous ionic liquid solutions was determined by using N-a-benzoyl-L-arginine ethyl ester as a substrate, and activity increases to about 127% was observed after 13 months storage. In addition, PPG400 has been recovered simply by heating and reused in the next extraction processes. This avoids the non-sustainable issue of highly salty water produced in the application of the polyethylene glycol (PEG) + salt and ionic liquid + salt ATPSs.
离子液体(ILs)作为常规挥发性有机溶剂的环保替代品,在工业过程中有着广泛的应用。然而,许多离子液体对生物体具有毒性且难以生物降解。在本工作中,设计和合成了一系列环境友好的胆碱类离子液体。研究发现,这些离子液体与热敏、无毒且可生物降解的聚丙二醇400(PPG400)可以形成水相双离子液体体系(ATPSs)。为了理解这些ATPSs的相形成过程及其在蛋白质提取/分离中的可能应用,在25 °C下测量了这些ATPSs的双结曲线和系线,并系统地研究了离子液体阴离子结构、蛋白质性质以及上相和下相浓度差异对一些典型蛋白质分配行为的影响。结果表明,牛血清白蛋白(BSA)、胰蛋白酶、木瓜蛋白酶和溶菌酶可以有效地富集到ATPSs的离子液体富集相中,在优化条件下单步提取效率可高达86.4-99.9%。此外,使用N-苯甲酰-L-精氨酸乙酯作为底物,测定了水和水合离子液体溶液中天然胰蛋白酶的酶活性,经过13个月的储存后活性增加到约127%。此外,PPG400通过简单加热即可回收并在下一次提取过程中重复使用。这避免了在应用聚乙二醇(PEG)+盐和离子液体+盐ATPSs时产生的高盐水量不可持续的问题。