Human polymorphonuclear leukocytes aminopeptidases.

In human polymorphonuclear leukocytes a methionine, leucine, arginine, phenylalanine and alanine aminopeptidase activities were detected, both in cytosol and secondary granules. All activities were EDTA sensitive and their pH optima were in the range of pH 6.5 to 8.6. In the cytosol two enzymes could be distinguished, broad substrate specificity aminopeptidase of pH 4.7-4.9 and a chloride dependent arginine aminopeptidase of pI 5.3-5.5. The granules contain aminopeptidase of pI 4.0-4.6 and of pI 9.8-10.2, different from those in the cytosol. Among them broad specificity aminopeptidases and possibly specific methionine and leucine aminopeptidases could be discerned.