Abstract
It is well known that mineral surfaces play an important role as catalysts for abiotic polymerization of amino acids to form peptides, which are the main components of the first self-replicating system. Understanding the mechanism behind the adsorption of simple amino acids on mineral surfaces is a topic of great interest not only in field of prebiotic evolution and but also in many other branches of material sciences. Various clay minerals have been suggested for studying how organic molecules were first synthesized in a prebiotic “inorganic” environment. Among them, pyrite (FeS2) is one of the most potential minerals as it possesses a highly reactive surface to drive molecular adsorption in prebiotic chemistry reactions. Recent theoretical experiments suggest that amino acids are adsorbed on the pyrite surface depending on its surface structures. However, these results have not been tested experimentally, and the exact mechanism of the specific interactions on this mineral has not been fully resolved yet at the molecular level. In this work, through quantitative force analysis with atomic force microscope (AFM) in which a single amino acid residue was mounted on the tip apex of AFM probe, we were able to find the reaction sites and study the interaction forces between the amino acid and the pyrite surface. Our results of Raman spectroscopic studies and force measurements with a well-designed AFM probe demonstrated for the first time that pyrite provided higher adsorption probabilities of amino acid residues for the chemical reactions at surfaces.
Highlights
Understanding the interaction between biomolecules, such as amino acids, peptides, or proteins, and mineral surfaces is currently a topic of importance in the fields of surface chemistry, catalysis, and prebiotic chemistry
Recent molecular dynamics studies [6]-[8] have suggested that pyrite surfaces resulting from crystallographic structure changes could selectively bind to simple amino acid residues
We performed thermal desorption spectroscopy (TDS) to check the desorption of sulfur atoms from pyrite surface, and the results showed the preferential desorption of sulfur atoms from the pyrite surface (Supplementary Information, Figure S1) indicating that sulfur vacancy sites are intrinsic in pyrite
Summary
Understanding the interaction between biomolecules, such as amino acids, peptides, or proteins, and mineral surfaces is currently a topic of importance in the fields of surface chemistry, catalysis, and prebiotic chemistry. Minerals are well established as catalysts for abiotic polymerization and can be very promising surfaces for studying biomolecule-surface processes [1]-[3] Among such minerals, pyrite (FeS2) is one of the most important and abundant sulfide minerals on earth. Recent molecular dynamics studies [6]-[8] have suggested that pyrite surfaces resulting from crystallographic structure changes could selectively bind to simple amino acid residues. These theoretical results regarding simple amino acid adsorption on pyrite have not been proved experimentally. We aim to investigate the affinity of simple amino acid adsorption on pyrite and to experimentally reveal the effects of pyrite surfaces on molecular bonding
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