A high molecular weight peptide hydrolase in erythrocytes.

1. A peptide hydrolase has been partially purified from the soluble fraction of erythrocyte lysates. 2. The enzyme has a molecular weight of approximately 600,000 and hydrolyses the chymotrypsin substrate glutaryl-Gly-Gly-Phe-7-amido-4-methylcoumarin (pH optimum 7.0) and the trypsin substrate CBZ-Gly-Gly-Arg-2-naphthylamide. The two activities could not be separated by the purification procedure used. 3. The activity towards glutaryl-Gly-Gly-Phe-7-amido-4-methylcoumarin in rat reticulocytes was four times that in mature erythrocytes. 4. Activity was abolished by 10 microM p-hydroxymercuriphenylsulphonic acid.