ABSTRACT: For years, polypeptide formation has fascinated
the scientific world because its understanding could lead to
one of the possible explanations for the origin of life. Anodic
oxidation of aliphatic α-amino acids in aqueous electrolytes
can result either in their decomposition or in their
polymerization into polypeptide. This behavior depends
experimentally on both amino acid concentration and pH.
The elucidation of the involved mechanisms remains a
challenge because of the multitude of products which can
be obtained. In this context, the electrochemical behavior of
glycine and alanine on a biased platinum surface was examined at the nanoscale by quantum electrochemistry via the effective
screening medium method. Several electrochemical systems with different concentrations and pH values have been explored.
Simulations of the anodic oxidation of the amino acids have not only confirmed their electropolymerization and decomposition
at high and low concentrations, respectively, but also have revealed unsuspected mechanisms at the origin of polypeptide
formation. This sheds new light on electrochemistry of α-amino acids, on occurrence of polypeptides, and more generally on