Distribution of prolyl oligopeptidase in human peripheral tissues and body fluids

Prolyl oligopeptidase (EC 3.4.21.26) activity was measured in human tissue homogenates and body fluids. The enzyme was ubiquitously present, revealing high activity in renal cortex, epithelial cells, fibroblasts, testis, lymphocytes and thrombocytes. The activity in the body fluids was low. Prolyl oligopeptidase activity was significant higher in tumours of prostate, lung and sigmoid, than in the healthy tissues. Sera of individuals suffering from HIV infection, malaria, prostate cancer or benign prostate hypertrophy contained lowered activity. Interestingly, the low serum activity during prostate carcinoma increased upon medical treatment with anti-androgens. This suggests hormonal control of the gene transcript. A positive correlation with angiotensin converting enzyme activity in hypertensive patients was demonstrated and this further supports the possible involvement of prolyl oligopeptidase in the renin-angiotensin system and in the pathogenesis of hypertension.