The processes of epimerization of individual peptide units in proteins and the concurrent cleavage of peptide bonds are modelled by heating some tetrapeptide and tetrapeptide derivatives to 148.5° C in pH 6.8 phosphate buffer. An excess of d-proline was observed during the heating of l-prolyl-l-leucylglycylglycine. The d/l ratio of proline attains a maximum value of 2.1 after 90 minutes. The excess d-proline is attributed to the formation of a 2.3: 1 ...
