D3.1 identification of the most reactive systems (toward condensation reactions) for further in-depth characterization
Two very promising systems have been identified, namely (Glu+Leu)/SiO2 and (Asp+Val)/SiO2. They show high-yield polymerization to linear oligopeptides up to n = 11 upon simple thermal activation to moderate temperatures (120-150°C). It breaks the record of polymer length for preparations in prebiotically realistic conditions. A preliminary report on these systems has been submitted for publication.
D3.2 and M3.2 Understanding of adsorption mechanisms on the systems selected in D3.1
Macroscopic studies, IR and preliminary NMR data indicate that the adsorption mechanisms on silica involve the formation of specific patterns of H-bonds. A Ph. D. thesis (Hagop Abadian) is being devoted to in-depth understanding of these adsorption mechanisms using advanced solid-state NMR methods. Additional information is available for adsorption mechanisms on clays (ion-exchange, except for acidic AAs), Fe oxides, and sulfides.
D3.3 and M3.3 Understanding the mechanisms of catalytic activation of biomolecules through their interaction with surface sites
Advanced Mass Spectrometric (FT-ICR) characterization of the peptides produced by catalytic activation of the amino acids has proved very useful to understand the peptide condensation reaction. Elementary steps involved in the formation of short peptides, and from there of longer ones, can be identified in this way.
A Ph.D. thesis will start in October 2018 with the aim to perfect the analytical methods applied to this problem and make them quantitative. Molecular level understanding of the mechanisms for each step will constitute the following stage in the elucidation of polypeptides formation, and is connected to D3.2.
M3.1 A list of model minerals classified with respect to their efficiency in catalyzing condensation reactions
Among tested materials, condensation reactions are most efficient on silica in terms of overall yield. They often, however, produce the evolutionary “dead end” DKP. Higher yields of oligopeptides are obtained on some Fe oxides, and on CuS (covellite). Swelling clay minerals (nontronite and montmorillonite) are not very efficient, and tend to activate decomposition reactions such as decarboxylation.