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Amorphous Silica-Promoted Lysine Dimerization: a Thermodynamic Prediction
Norio Kitadai1, Kumiko Nishiuchi2, Akari Nishii3
1Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo, 152-8550, Japan. nkitadai@elsi.jp.
Summary
Mineral surfaces significantly enhance amino acid (L-lysine) dimerization, a key step in the origin of life. This study quanties these interactions, revealing optimal conditions for prebiotic peptide bond formation on silica surfaces.
Area of Science:
- Geochemistry
- Astrobiology
- Origin of Life Studies
Background:
- Mineral surfaces are hypothesized to be critical for abiotic amino acid polymerization before life emerged.
- Understanding amino acid-mineral interactions under various environmental conditions is crucial for pinpointing early Earth's prebiotic environments.
Purpose of the Study:
- To experimentally investigate the adsorption of L-lysine (Lys) and its dimer (LysLys) on amorphous silica.
- To quantify the influence of environmental factors (pH, ionic strength, concentration, solid/water ratio) on Lys dimerization.
- To model these interactions using the extended triple-layer model (ETLM) and predict LysLys formation.
Main Methods:
- Experimental adsorption studies of L-lysine and L-lysine dimer on amorphous silica.
- Determination of reaction stoichiometries and equilibrium constants using the extended triple-layer model (ETLM).
- Calculation of LysLys equilibrium concentrations under diverse aqueous conditions using ETLM parameters and bulk water peptide bond formation constants.
Main Results:
- Amorphous silica surfaces significantly promote L-lysine dimerization.
- The extent of Lys dimerization is highly sensitive to environmental parameters like pH and ionic strength.
- Under specific conditions (pH 9, 1 mM NaCl), silica increased LysLys concentration approximately 50-fold compared to bulk water.
Conclusions:
- Silica surfaces act as catalysts for amino acid dimerization, influencing the prebiotic formation of peptides.
- The ETLM provides a versatile framework for modeling biomolecule-mineral interactions.
- This research offers constraints for identifying plausible geological settings for early chemical evolution and the origin of life.
