Molecular mechanisms of pH-tunable stability and surface coverage of polypeptide films
Molecular mechanisms of pH-tunable stability and surface coverage of polypeptide films
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DOI：
10.1016/j.apsusc.2023.156331
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发表时间：
2023-01-12
影响因子：
6.7
通讯作者：
Sammalkorpi, Maria
中科院分区：
文献类型：
--
作者：
Harmat, Adam L.;Morga, Maria;Sammalkorpi, Maria
采用流动电位法和石英晶体微天平法，结合全原子分子动力学模拟，研究了两种碱性同聚多肽--聚L-赖氨酸（PLL）和聚L-精氨酸（PARG）在α-石英表面的吸附与pH的关系.我们报告说，所观察到的吸附行为上升，从相互作用的i）的变化，在可能的肽表面离子对之间的带电部分和ii）排斥的多肽分子之间的静电相互作用。对于低pH值，多肽吸附最强，形成稳定的单分子膜。然而，多肽之间的静电排斥导致相对低的最大表面覆盖度。另一方面，更高的pH值导致更弱的结合，但显着致密，肽膜有限的稳定性。模拟结果表明，静电相互作用是吸附的主要驱动力，而氢键和非特异性相互作用也作出了贡献。此外，形成带正电的离子吸附层的带负电的石英表面的抗衡离子的重要作用被突出。在带电表面处的凝聚钠离子的离子释放经由多肽吸附的置换发生。这项工作所揭示的机制提供了系统的指导方针，工程活性表面的带电肽与控制的表面覆盖和可逆结合。
Streaming potential and quartz crystal microbalance measurements, combined with all-atom molecular dynamics simulations, were used to study the pH dependency of the adsorption of two basic homopolypeptides, poly-L-lysine (PLL) and poly-L-arginine (PARG), on alpha-quartz surface. We report that the observed adsorption behavior rises from an interplay of i) the change in the number of possible peptide-surface ion pairs between the charged moieties and ii) repulsive electrostatic interactions between the polypeptide molecules. For low pH values, polypeptide adsorption was strongest and stable monolayers were formed. However, electrostatic repulsion between the polypeptides led to a relatively low maximum surface coverage. On the other hand, higher pH led to more weakly bound, but significantly denser, peptide films with limited stability. Simulations indicate that electrostatic interactions are the main driving force for adsorption, while hydrogen bonding and non-specific interactions also contribute. Additionally, the important role of the counterions of the negatively charged quartz surface that form a positively charged ion adlayer is highlighted. Ion release of the condensed sodium ions at the charged surface occurs via displacement by polypeptide adsorption. The mechanisms revealed by this work provide systematic guidelines to engineering active surfaces of charged peptides with controlled surface coverage and reversible binding.