An inhibitor for post-proline cleaving enzyme; distribution and partial purification from porcine pancreas.

An inhibitor(s) for post-proline cleaving enzyme was checked by using a fluorogenic substrate, Z-Gly-Pro-4-methyl coumarinamide, and was found to be distributed widely in rat and porcine organs. The highest inhibitory activity on the enzyme was observed in pancreas and the inhibitor was partially purified from porcine pancreas extract by heat treatment, chromatographies on DEAE-Sephadex and Sephadex G-50 and affinity chromatography on trypsin-Sepharose. This inhibitor was very stable against temperature, pH and trichloroacetic acid treatment. The molecular weight was estimated to be 6500 by gel filtration. This inhibitor was highly specific for prolyl endopeptidases from mammals and Flavobacterium and inhibited the enzyme competitively. It acted neither on proline specific exopeptidases such as dipeptidyl aminopeptidase IV, proline aminopeptidase, prolidase, nor usual endopeptidases such as trypsin and alpha-chymotrypsin.