Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Moto-oka, Fukuoka 819-0395, Japan.
Org Biomol Chem. 2010 Jun 28;8(13):2887-99. doi: 10.1039/b926130c. Epub 2010 May 6.
As environmentally benign "green" solvents, room temperature ionic liquids (ILs) have been used as solvents or (co)solvents in biocatalytic reactions and processes for a decade. The technological utility of enzymes can be enhanced greatly by their use in ionic liquids (ILs) rather than in conventional organic solvents or in their natural aqueous reaction media. In fact, the combination of green properties and unique tailor-made physicochemical properties make ILs excellent non-aqueous solvents for enzymatic catalysis with numerous advantages over other solvents, including high conversion rates, high selectivity, better enzyme stability, as well as better recoverability and recyclability. However, in many cases, particularly in hydrophilic ILs, enzymes show relative instability and/or lower activity compared with conventional solvents. To improve the enzyme activity as well as stability in ILs, various attempts have been made by modifying the form of the enzymes. Examples are enzyme immobilization onto support materials via adsorption or multipoint attachment, lyophilization in the presence of stabilizing agents, chemical modification with stabilizing agents, formation of cross-linked enzyme aggregates, pretreatment with polar organic solvents or enzymes combined with suitable surfactants to form microemulsions. The use of these enzyme preparations in ILs can dramatically increase the solvent tolerance, enhance activity as well as stability, and improve enantioselectivity. This perspective highlights a number of pronounced strategies being used successfully for activation and stabilization of enzymes in non-aqueous ILs media. This review is not intended to be comprehensive, but rather to present a general overview of the potential approaches to activate enzymes for diverse enzymatic processes and biotransformations in ILs.
作为环境友好的“绿色”溶剂，室温离子液体（ILs）已在生物催化反应和过程中作为溶剂或（共）溶剂使用了十年。通过在离子液体（ILs）中而不是在常规有机溶剂或其天然水相反应介质中使用酶，可以大大增强酶的技术实用性。事实上，绿色特性和独特的定制物理化学特性的结合使 ILs 成为酶催化的出色非水溶剂，与其他溶剂相比具有许多优势，包括高转化率、高选择性、更好的酶稳定性，以及更好的可回收性和可循环性。然而，在许多情况下，特别是在亲水性 ILs 中，与常规溶剂相比，酶表现出相对不稳定性和/或较低的活性。为了提高酶在 ILs 中的活性和稳定性，已经通过修饰酶的形式进行了各种尝试。例如，通过吸附或多点附着将酶固定在载体材料上、在稳定剂存在下进行冷冻干燥、用稳定剂进行化学修饰、形成交联酶聚集体、用极性有机溶剂预处理或与合适的表面活性剂结合形成微乳液。这些酶制剂在 ILs 中的使用可以显著提高溶剂耐受性、增强活性和稳定性，并提高对映选择性。本文重点介绍了一些成功用于在非水 IL 介质中激活和稳定酶的显著策略。本综述并非旨在全面涵盖，但旨在概述在 ILs 中激活酶以用于各种酶促过程和生物转化的潜在方法。
