We investigate the hypothesis that mineral/water interfaces played a crucial catalytic role in peptide formation by promoting the self-assembly of amino acids. Using force-field-based molecular dynamics simulations, we demonstrate that the $\alpha$-alumina (0001) surface exhibits an affinity of 4 kBT for individual glycine or GG dipeptide molecules, due to hydrogen bonds formed at both the C- and N-termini. In simulations with multiple glycine molecules, surface-bound glycine enhances further adsorption, leading to the formation of long chains connected by hydrogen bonds between the carboxyl and amine groups of glycine molecules. The probability of forming long amino acid chains is examined using metadynamics enhanced sampling and a modified Flory theory. We find that the likelihood of observing chains longer than 10 glycine units increases by at least 5 orders of magnitude at the surface compared to the bulk. This surface-driven assembly is primarily due to local high density and alignment with the alumina surface pattern, resulting in a competition between enthalpy and entropy effects on adsorption. The formation of these chains necessitates the removal of coordinated water molecules. Importantly, our findings reveal that when dipeptides are present, only the N-terminus forms hydrogen bonds with the surface, suggesting that the surface may disfavor the backward hydrolysis of newly formed peptides. Together, these results propose a model for how mineral surfaces can induce configuration-specific assembly of amino acids, thereby promoting condensation reactions.

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关于 α-氧化铝在生命起源中的作用：氨基酸的表面驱动组装


我们研究了矿/水界面通过促进氨基酸的自组装在肽形成中起关键催化作用的假设。使用基于力场的分子动力学模拟，我们证明 $\alpha$-氧化铝 （0001） 表面对单个甘氨酸或 GG 二肽分子表现出 4 kBT 的亲和力，这是由于在 C 端和 N 端形成的氢键。在具有多个甘氨酸分子的模拟中，表面结合的甘氨酸增强了进一步的吸附，导致甘氨酸分子的羧基和胺基之间形成由氢键连接的长链。使用宏动力学增强采样和改进的 Flory 理论来检查形成长氨基酸链的可能性。我们发现，与本体相比，在表面观察到长度超过 10 甘氨酸单位的链的可能性至少增加了 5 个数量级。这种表面驱动的组装主要是由于局部高密度和与氧化铝表面图案的对齐，导致吸附的焓效应和熵效应之间的竞争。这些链的形成需要去除配位的水分子。重要的是，我们的研究结果表明，当存在二肽时，只有 N 端与表面形成氢键，这表明表面可能不利于新形成的肽的向后水解。总之，这些结果提出了一个模型，说明矿物表面如何诱导氨基酸的构型特异性组装，从而促进缩合反应。