Prolylcarboxypeptidase: A Recently Described Lysosomal Enzyme.
OKLAHOMA UNIV MEDICAL CENTER OKLAHOMA CITY
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Prolylcarboxypeptidase PCP was first found in the kidney. In addition to the kidney, PCP occurs in human plasma or erythrocytes. PCP occurs in a lysosomal fraction of swine kidney cortex and of human granulocytes. Table III shows the distribution of PCP activity among fractions of homogenized swine kidney cortex. PCP was concentrated in the same fraction that contained most of the beta-glucuronidase activity. Because renin is also particle-bound, occurs in the kidney, and has an acidic pH optimum, it is possible that PCP accompanies renin in crude preparations extracted from the kidney. Since PCP inactivates angiotensin II, it may contribute to a homeostatic balance. The presence of the enzyme in a lysosomal fraction of leukocytes and its ability to cleave proline bonds may suggest additional roles for PCP--for example, in connective tissue metabolism in inflammation. Author