ENZYMES IN HOG KIDNEY HYDROLYZING AMINO ACID NAPHTHYLAMIDES

Hydrolysis of β-naphthylamides of a number of amino acids and dipeptides and of a number of di- and tripeptides by hog kidney homogenate and by fractions obtained by various fractionation procedures has been studied. The substrates were found to be split by a soluble, apparently sulfhydryl-dependent enzyme, and by a particle-bound, metal-activated enzyme. The former constituted only a small part of the total activity. The latter was subfractionated by starch gel electrophoresis into two fractions with identical characteristics. The soluble and particle-bound enzymes differed also in their substrate specificity. The latter enzyme was solubilized, partially purified, characterized by some modifier compounds and compared with enzyme preparations obtained by various fractionation procedures presented by other investigators. Thus enzyme showed ion-determined substrate specificity, i.e., hydrolysis of some of the amino acid naphthylamides was found to be activated by Co ++ while the hydrolysis of others was inhibited by the same metal ion.