Inhibition of D-Amino-acid Oxidase

Abstract

PEPTIDES containing D-amino-acids are not attacked by D-amino-acid oxidase^1,2. We have found that the action of pig kidney D-amino-acid oxidase on DL-leucine was inhibited by DL-leucinamide, DL-loucylglycine, DL-leucylglycylglycine, and by glycyl-DL-leucino. These compounds also inhibited the enzymic oxidation of DL-valine and DL-phenylalanine. Thus, DL-leucinamide when added to DL-leuoine, DL-valine or DL-phenylalanine in a molar ratio 5 : 1 inhibited the oxidation by 35–45 per cent. DL-Leucylglycine inhibited the oxidation of DL-leucine by 40–45 per cent, of DL-phenylalanino by 50 per cent, and of DL-valine by 60 per cent. DL-Leucylglycylglycine inhibited the oxidation of DL-phenylalanino by 25 per cent, of DL-leucine by 30 ger cent, and of DL-valine by 65 per cent. Glycyl-DL-leucine gave similar results. With glycylglycine no inhibition was obtained.