A fundamental and still unanswered question about the origin of life concerns the polymerization of amino acids in prebiotic conditions: the polypeptide condensation reaction shows exceedingly large kinetic barriers and is unlikely to occur spontaneously in solution. This observation is at odds with several lines of evidence suggesting that formation of ancestral proteins predates the emergence of cellular machineries. One of the most accepted hypotheses to solve this conundrum posits that mineral/water interfaces played a crucial catalytic role in peptide formation. In this work we investigate self-assembly of amino acids at α-alumina(0001)/water interfaces. Using force-field based molecular dynamics simulations and metadynamics, we show that the solid surface has moderate affinity for isolated amino acids. For both isolated glycine and glycine-glycine dipeptide, the most stable binding mode is such that both C- and N-terminus are simultaneously in contact with the surface. Simulations at 0.3 M concentration of glycine show a templating effect of the solid, whereby adsorbed amino acids form long chains with C- and N-termini connected by H-bonds. Pairs of amino acids are thus assembled in a geometry capable of sustaining a condensation reaction. Importantly, an alternate configuration is observed in which only the N-terminus donates H-bonds to the alumina oxygens. In this orthogonal orientation of the molecule, the peptide bond of the glycine-glycine dipeptide is far from the mineral surface and completely solvent exposed. We hypothesize that a transition to this conformational state prevents surface-catalyzed backward hydrolysis of the newly formed peptide. Despite several open questions, our work provides important preliminary insight on how mineral surfaces may induce configuration-specific assembly of amino acids and thus promote condensation reactions.<br/>

On the role of α-alumina in the origin of life: Surface driven assembly of amino acids

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.