Two types of oligopeptides: homopeptide DIPP-(aa(1))(n) and heteropeptide D
IPP-(aa(1))(n-1)-aa(2) formed when the aqueous solution of N-phosphoamino a
cid (DIPP-aa(1)) and amino acid (aa(2)) was radiated by infrared light. An
intramolecular mixed carboxylic-phosphoric-anhydride intermediate might exi
st in the peptide formation process.