A predictive equation based on extrathermodynamic assumptions is proposed, that allows the prediction of the degree of epimerization in tripeptide model reactions of condensation of peptide segments as a function of the primary structure. The experimental validation of this equation is presented in the field of the 125 tripeptides containing alanine, leucine, phenylalanine, valine and isoleucine, the prediction requires 13 epimerization ...