Department of Chemistry, Shivaji University, Kolhapur 416004, Maharashtra, India.
Department of Chemistry, Rajaram College, Kolhapur 416004, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2022 Jan 15;265:120378. doi: 10.1016/j.saa.2021.120378. Epub 2021 Sep 10.
The structure of water, especially around the solute is thought to play an important role in many biological and chemical processes. Water-peptide and cosolvent-peptide interactions are crucial in determining the structure and function of protein molecules. In this work, we present the H-bonding analysis for model peptides like glycyl-glycine (gly-gly), glycine-ւ-valine (gly-val), glycyl-ւ-leucine (gly-leu) and triglycine (trigly) and triethylammonium based carboxylate protic ionic liquids (PILs) in aqueous solutions as well as for peptides in ∼0.2 mol·L of aqueous PIL solutions in the spectral range of 7800-5500 cm using Fourier transform near-infrared (FT-NIR) spectroscopy at 298.15 K. The hydration numbers for peptides and PILs were obtained using NIR method of simultaneous estimation of hydration spectrum and hydration number of a solute dissolved in water. The H-bond of water molecules around peptides and PILs are found to be stronger and shorter than those in pure liquid water. We observe that the hydration shell around zwitterions is a clathrate-like cluster of water in which ions entrap. Watery network analysis confirms that singly H-bonded species or NHBs changes to partial or distorted ice-like structures of water in the hydration shell of PILs. The overall water H-bonding in the hydration sphere of PILs increases in the order TEAF < TEAA < TEAG < TEAPy ≈ TEAP < TEAB. The influence of PILs on hydration behavior of peptides is explored in terms of H-bonding, cooperativity, hydrophobicity, water structural changes, ionic interactions etc.
水的结构，特别是在溶质周围，被认为在许多生物和化学过程中起着重要作用。水-肽和共溶剂-肽相互作用对于确定蛋白质分子的结构和功能至关重要。在这项工作中，我们在 298.15 K 下使用傅里叶变换近红外（FT-NIR）光谱，在 7800-5500 cm 的光谱范围内，对甘氨酰-甘氨酸（gly-gly）、甘氨酸-缬氨酸（gly-val）、甘氨酰-亮氨酸（gly-leu）和三甘氨酸（trigly）等模型肽以及在约 0.2 mol·L 的水溶液中肽的氢键分析，基于三乙基铵的羧酸质子离子液体（PILs）。使用 NIR 法同时估算溶解在水中的溶质的水合光谱和水合数，获得了肽和 PIL 的水合数。发现肽和 PIL 周围水分子的氢键比纯液态水中的氢键更强、更短。我们观察到两性离子周围的水合壳是水的笼状簇，其中离子被捕获。含水网络分析证实，单氢键合物种或 NHBs 会在 PIL 的水合壳中部分或扭曲成类似冰的水结构。PILs 在水合球中的整体水氢键合程度按 TEAF < TEAA < TEAG < TEAPy ≈ TEAP < TEAB 的顺序增加。从氢键合、协同作用、疏水性、水结构变化、离子相互作用等方面探讨了 PILs 对肽水合行为的影响。
