La Photooxydation Du Groupe Peptide—ii. Peptides Et Polyaminoacides a l‘ÉTAT Solide*

The determination of glyoxylic and pyruvic acids in oligo‐and poly‐, glycine and alanine shows that the peptide group is photooxydized, probably with the radical ‐NH‐CR‐CO‐ as an intermediate. The characterisation of pyruvic acid in glutathione and oxydized glutathione confirms the photolysis of the C‐S bond in combined cysteine and cystine. Finally, a comparison of the photoreactivity of peptides of the types aliphatic amino acid‐aromatic amino acid and aromatic amino acid‐aliphatic amino acid allows us to propose a selective mechanism for the transfer of excitation energy from the phenyl group to the preceding amino acid residue in the polypeptide chain.