ANGIONTENSIN-CONVERTING ENZYME ACTIVITY IN DUNNING RAT PROSTATE TUMOR

A dipeptidyl carboxypeptidase activity in the Dunning rat prostate tumor was characterized. This enzyme demonstrated the most prominent properties of angiotensin converting enzyme (ACE): that is, it was stimulated by NaCl and Co 2+ and was potently inhibited by captopril. The enzyme solubilized by Triton X-100 had a molecular mass of 110 kDa as determined by gel filtration chromatography. The specific activity of ACE did not change with castration, indicating that ACE activities are not controlled by androgen. The role of ACE in the prostate and its tumors is not understood, but the ability of this enzyme to hydrolyze a number of bioactive peptides suggests that it may function in controlling the molecular forms or activity of regulatory peptides.