NMR, Inorganic & Physical Chemistry Laboratory, CSIR-Central Leather Research Institute, Adyar, Chennai-600020, India.
Academy of Scientific and Innovative Research (AcSIR), CSIR-CLRI Campus, Chennai-600020, India and Organic & Bioorganic Chemistry Laboratory, CSIR-Central Leather Research Institute, Adyar, Chennai-600020, India.
Phys Chem Chem Phys. 2018 Apr 4;20(14):9256-9268. doi: 10.1039/C7CP08298C.
The interaction of ionic liquid (IL) with protein is now becoming important as it stabilizes the protein due to the selective cation-anion combination of the IL. The binding and dynamics of the green solvents such as imidazole alkyl sulfate based ILs, viz., 1-butyl-3-methylimidazolium alkyl [where alkyl = hydrogen, methyl, octyl and dodecyl] sulfate, with two distinct model proteins, namely human serum albumin (HSA) and collagen in aqueous solution, have been investigated with the aid of solution nuclear magnetic resonance (NMR). Interactions of ILs with HSA and collagen have been probed at the atomistic level through NMR determined parameters, such as 1H line-shapes, selective and non-selective spin-lattice relaxation times (T1SEL & T1NS) and spin-spin relaxation times (T2). Furthermore, saturation transfer difference (STD) NMR has been used to monitor the spatial proximities of ILs with HSA and collagen. The results indicate that despite the type of protein (HSA or collagen), STD NMR of protein-IL mixtures exhibits responses only from the anionic part of the selected ILs. Also, a combination of T1SEL and T1NS measurements indicates the genuine protein-IL interaction. Furthermore, it was observed that the global binding affinity between IL and proteins is enhanced with an increase in alkyl chain length of the anionic portion of the IL. The present study thus highlights the role of the anionic part of ILs in the interaction with the selected proteins. The outcome of the present study provides an opportunity to design new ILs with a judicious choice of anionic and cationic parts for targeted functionalities.
离子液体（IL）与蛋白质的相互作用正变得越来越重要，因为它通过 IL 的选择性阳离子-阴离子组合稳定蛋白质。目前，已借助溶液核磁共振（NMR）研究了绿色溶剂（如基于咪唑烷基硫酸盐的 IL，即 1-丁基-3-甲基咪唑烷基[其中烷基=氢、甲基、辛基和十二烷基]硫酸盐）与两种不同模型蛋白质（即人血清白蛋白（HSA）和胶原蛋白）在水溶液中的结合和动态。通过 NMR 确定的参数（如 1H 线宽、选择性和非选择性自旋晶格弛豫时间（T1SEL 和 T1NS）和自旋-自旋弛豫时间（T2）），在原子水平上探测了 IL 与 HSA 和胶原蛋白的相互作用。此外，还使用饱和转移差（STD）NMR 来监测 IL 与 HSA 和胶原蛋白的空间接近程度。结果表明，尽管蛋白质的类型（HSA 或胶原蛋白）不同，但蛋白质-IL 混合物的 STD NMR 仅显示所选 IL 的阴离子部分的响应。此外，T1SEL 和 T1NS 测量的组合表明存在真正的蛋白质-IL 相互作用。此外，还观察到 IL 与蛋白质之间的整体结合亲和力随着 IL 阴离子部分的烷基链长度的增加而增强。因此，本研究强调了 IL 的阴离子部分在与所选蛋白质相互作用中的作用。本研究的结果为设计具有目标功能的新 IL 提供了机会，可通过明智地选择阴离子和阳离子部分来实现。
