Enzymhemmng und Enzymblockierung. 2. Mitteilung (Antipodische Hemmung)

Abstract

The peptidase enzyme soln. was - prepared by extracting 180 g. of pig intestinal mucosa with 600 g. 70% glycerin in the ice box overnight and filtering the mixture. The filtrate was the enzyme soln. used. The reaction mixtures usually contained 4 ml. substrate (M/10 1-leucylgly-cine or racemic leucylglycine) pH 7.4, 2-12 ml. inhibitor soln. (M/5 d-leucylglycine or glycine) pH 7.4, 0.3 ml. enzyme soln., and sufficient M/15 phosphate buffer to make a total vol. of 16 ml. The mixtures were incubated at 38[degree] for 0-16 hrs. The amt. of peptide split was detd. by Sorensen''s formol titration method. The splitting of 1-leucyl-glycine was prevented or blocked by 9-12 ml. M/5 d-leucylglycine. The splitting of glycylglycine was also suppressed by d-leucylglycine and to a slight extent by glycine. The affinity of the dipeptidase seemed to be greater towards the unnatural d-di-peptide than towards the natural 1-dipeptide. d-Leucylglycine was not split by the peptidase. The free amino acids, glycine, d- and 1-leucine did not affect the activity of the dipeptidase. The oxidation of d-alanine by d-amino acid oxidase prepared from pig kidney was not affected by 1-alanine in 25 times the conc, of d-alanine.