Discipline of Chemistry, Indian Institute of Technology Indore, Indore, Madhya Pradesh 453552, India.
Phys Chem Chem Phys. 2020 Feb 14;22(6):3234-3244. doi: 10.1039/c9cp06188f. Epub 2020 Jan 29.
In the present contribution, we investigate the interactions of lipid bilayer membranes of different charges and different phase states with aliphatic amino acids of varying charge (aspartic acid, glutamic acid, arginine and lysine) and hydrophobicity (serine, leucine and valine) by steady state and time-resolved spectroscopic techniques, dynamic light scattering (DLS) measurements and confocal imaging (CLSM). The study reveals that negatively charged amino acids such as aspartic acid and glutamic acid interact strongly with the lipid membranes particularly with negatively charged lipid membranes by stabilizing their gel phase. On the other hand, positively charged amino acids bring in hydration in the membranes. We explain this unique observation by the shift in pK of amino acids in the vicinity of the lipid membranes and solvation and desolvation processes in the light of recent computer simulations. We also find that hydrogen bonding plays a significant role in governing the interaction of aliphatic amino acids with zwitterionic lipid membranes. The more polar serine bearing a hydroxyl group at the terminal carbon offers a stronger interaction with the lipid bilayer membranes as compared to its analogues leucine and valine, which are hydrophobic in nature.
在本研究中，我们采用稳态和时间分辨光谱技术、动态光散射（DLS）测量和共聚焦成像（CLSM）研究了不同电荷和不同相态的脂质双层膜与带电荷（天冬氨酸、谷氨酸、精氨酸和赖氨酸）和疏水性（丝氨酸、亮氨酸和缬氨酸）不同的脂肪族氨基酸之间的相互作用。研究表明，带负电荷的氨基酸（如天冬氨酸和谷氨酸）与脂质膜强烈相互作用，特别是与带负电荷的脂质膜相互作用，稳定其凝胶相。另一方面，带正电荷的氨基酸会使膜水化。根据最近的计算机模拟，我们通过氨基酸在脂质膜附近的 pK 值的变化以及溶剂化和解溶剂化过程来解释这种独特的观察结果。我们还发现氢键在控制脂肪族氨基酸与两性离子脂质膜的相互作用方面起着重要作用。末端碳原子上带有羟基的极性更强的丝氨酸与脂质双层膜的相互作用比疏水性的亮氨酸和缬氨酸更强。
