The ubiquity of amino acids in carbonaceous meteorites has suggested that amino acids are widespread in the Universe, serving as a common class of components for the emergence of life. However, parameters for modeling amino acid polymerization at mineral–water interfaces remain limited, although the interfacial conditions inevitably exist on planets with surface liquid water. Here, we present a set of extended triple-layer model parameters for aspartate (Asp) and aspartyl-aspartate (AspAsp) adsorptions on ferrihydrite, anatase, and γ-alumina determined based on the experimental adsorption data. By combining the parameters with the reported thermodynamic constants for amino acid polymerization in water, the impacts of these minerals on Asp dimerization are calculable over a wide range of environmental conditions. It was predicted, for example, that ferrihydrite strongly increases the AspAsp/Asp equilibrium ratio in neutral to acidic pH; the ratio in the adsorbed state reaches 40% even from a low Asp concentration (0.1 mM) at pH 4. This percentage is approximately 5 × 107 times higher than that attainable without mineral (8.5 × 10–6%). Our exemplified approach enables us to screen wide environmental settings for abiotic peptide synthesis from a thermodynamic perspective, thereby narrowing down the geochemical situations to be explored for life’s origin on Earth and Earth-like habitable planets.
Thermodynamic Impact of Mineral Surfaces on Amino Acid Polymerization: Aspartate Dimerization on Ferrihydrite, Anatase and γ-alumina
