Performance of tetraalkylammonium-based ionic liquids as constituents of aqueous biphasic systems in the extraction of ovalbumin and lysozyme
Performance of tetraalkylammonium-based ionic liquids as constituents of aqueous biphasic systems in the extraction of ovalbumin and lysozyme
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DOI：
10.1016/j.seppur.2019.116019
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发表时间：
2020-02-15
影响因子：
8.6
通讯作者：
Freire, Mara G.
中科院分区：
文献类型：
--
作者：
Belchior, Diana C., V;Quental, Maria, V;Freire, Mara G.
基于离子液体的水相两相体系（基于离子液体的ABS）已被描述为用于提取和分离蛋白质的有前途的平台。然而，基于咪唑的离子液体一直是优选的选择，这可能会引起一些生物相容性和生物降解性的问题。在这项工作中，新的ABS组成的四烷基铵基离子液体和磷酸钾溶液在不同的pH值（pH = 7，8，9和13，使用K2 HPO 4/KH 2 PO 4或K3 PO 4）的两种蛋白质，即卵清蛋白和溶菌酶的提取效率和回收率方面进行了研究。选择这些蛋白质是因为它们在几个领域中的广泛应用，存在于鸡蛋白色中。在pH 7，完全提取和回收的溶菌酶的IL-丰富的相实现在所有系统中，然而，低回收率的卵清蛋白与ABS形成的其具有较长的烷基侧链。此外，在蛋白质的等电点以上的pH值的增加是有害的，它们在富含IL的阶段的恢复。为了表征可以最大化蛋白质回收的分子水平机制，进行了分子对接研究，表明优先与这些蛋白质建立疏水相互作用的是那些导致其聚集和较低回收率的分子。最后，显示了通过冰冷的乙醇沉淀从富含IL的相中回收蛋白质，其中可以回收高达99%的溶菌酶。这些结果支持足够的IL-为基础的ABS提取卵清蛋白和溶菌酶的可行性和回收稳定的蛋白质从IL-丰富的阶段到一个足够的缓冲水溶液的可能性，从而有助于有效的分离过程的设计。
Ionic-liquid-based aqueous biphasic systems (IL-based ABS) have been described as promising platforms for the extraction and separation of proteins. However, imidazolium-based ILs have been the preferred choice, which may raise some biocompatibility and biodegradability concerns. In this work, novel ABS composed of tetraalkylammonium-based ILs and potassium phosphate solutions at different pH values (pH = 7, 8, 9 and 13, using K2HPO4/KH2PO4 or K3PO4) were investigated in terms of extraction efficiency and recovery yield for two proteins, namely ovalbumin and lysozyme. These proteins were selected due to their wide application in several sectors, being present in egg white. At pH 7, the complete extraction and recovery of lysozyme to the IL-rich phase are achieved in all systems; however, low recovery yields of ovalbumin are obtained with ABS formed by Its with longer alkyl side chains. Furthermore, an increase in the pH above the proteins isoelectric point is deleterious for their recovery in the IL-rich phase. In order to characterize the molecular-level mechanisms that could maximize the proteins recovery, molecular docking studies were carried out, showing that Its that preferentially establish hydrophobic interactions with these proteins are those that lead to their aggregation and lower recovery yields. Finally, it is shown the proteins recovery from the IL-rich phase by ice cold ethanol precipitation, where up to 99% of lysozyme can be recovered. These results support the viability of adequate IL-based ABS to extract ovalbumin and lysozyme and the possibility of recovering stable proteins from the IL-rich phase into an adequate buffered aqueous solution, thus contributing to the design of effective separation processes.