Investigation of the in vitro effect of some active substance that prevent hypertension on angiotensin converting enzyme (ace ec 3.4.15.1) purified from bovine lung by affinity chromatography method

Angiotensin converting enzyme (ACE EC 3.4.15.1) synthesized by endothelial cells and responsible for the regulation of blood pressure was purified from the bovine lung by affinity chromatography method and purification rate of angiotensin converting enzyme of bovine lung was calculated as 1748 fold. Optimum temperature and pH for the purified ACE were found to be 35-40 oC and 7.6, respectively. By means of SDS-PAGE was seen to have three subunits at 57 kDa, 66 kDa and 190 kDa molecular weight of ACE. Then, the molecular weight of the enzyme was then determined by gel filtration chromatography and the molecular weight of ACE was calculated as 303 kDa. The effects of ACE inhibitors lisinopril, captopril, fosinopril, βeta-blocker atenolol, propranolol, diuretics triamterene, spironolactone and indapamide on ACE activity were investigated. However, spironolactone and indapamide could not be studied due to dissolution in pure water. While ACE inhibitors lisinopril, captopril, fosinopril and diuretic, triamterene showed an inhibitory effect on ACE activity, B-blockers showed no effect. Active substance such as lisinopril, captopril, fosinopril and triamterenin were noncompetitive effect on ACE activity and graphs were drawn. IC50 values of these compounds were calculated from the graphical equation. IC50 values of these active substances showing inhibition effect on bovine lung ACE activity were calculated as 4.085 nM, 0.835 nM, 1.159 µM and 227 µM, respectively. Ki constants for lisinopril, captopril, fosinopril and triamterene were also calculated as 6.449 nM, 1.057 nM, 1.675 µM and 419.5 µM, respectively. Captopril showed the highest inhibitory activity with an IC50 value of 0.835 nM.