Zur sterischen Spezifität der Dipeptidase und Aminopeptidase

Abstract

To prepare the organ glycerin extracts, human carcinoma etc. obtained at operation, or organs from animals were ground with sand, and shaken frequently for 24 hrs. at 0[degree] with 1 part 87% glycerin and 2 parts phosphate buffer. The filtrate was used for the expts. The reaction mixtures contained 1 ml. of the glycerin extract, 1 ml. of peptide soln. and 2 ml. of phosphate buffer, pH 7.4. The course of the hydrolysis of the peptides was folldwed by Warburg''s manometric method, and by the titration method. Both components of d,l-leucylglycine were hydrolyzed about equally by the glycerin extracts of almost all tissues except normal pancreas and muscle. Since carbobenzoxyglycyl-d, l-alanine and carbobenzoxyglycyl-1-leucine were not hydrolyzed by the extracts, the hydrolysis of the d-dipeptides was not caused by carboxypeptidase. The enzymes in the extracts which caused the hydrolysis were not identified. The influence of the constitution of the peptides was shown by the fact that the extracts from the different organs hydrolyzed the d-components of d,l-alanyl-, aminobutyryl-, valyl- and leucylglycylglycine, respectively, 28.8-61.4%, 11.5-18.8%, 0.7-7.4% and 0.0-6.0%. The d-component of d,l-aminobutyrylglycylglycine was not hydrolyzed by normal human serum but was by serum from patients with carcinoma, tuberculosis, contracted kidney etc. The appearance of d-peptide hydrolyzing enzymes in serum was thought to be due in part to necrotic processes in the body.