ENKEPHALIN-DEGRADING DIPEPTIDYLCARBOXYPEPTIDASES IN HUMAN AND CAVIA-PORCELLUS PLASMA

1. The dipeptidylcarboxypeptidases that degrade leucine enkephalin in human and guinea pig plasma were studied by kinetic and chromatographi c techniques. 2. The extremely rapid degradation of enkephalins in Cav ia plasma seems to be caused by both increased activity of enzymes and reduced role of inhibitors. 3. The increased role of dipeptidylcarbox ypeptidases in Cavia as compared to Homo appears prevalently caused by the presence in the former species of a considerable number of very a ctive enzymes. 4. The sum of these data indicates the existence of not iceable intraspecific differences either in peptide-degrading enzymes present in plasma, or in plasma peptides, or in both.