Inhibition effect of nicotinamide (vitamin B3) and reduced glutathione (GSH) peptide on angiotensin-converting enzyme activity purified from sheep kidney.

Angiotensin-converting enzyme (ACE, EC 3.4.15.1) plays a significant role in blood pressure regulation and inhibition of this enzyme is one of the significant drug targets for the treatment of hypertension. In this work, ACE was purified from sheep kidneys with the affinity chromatography method in one step. The purity and molecular weight of ACE were designated using the SDS-PAGE method and observed two bands at around 60 kDa and 70 kDa on the gel. The effects of nicotinamide (vitamin B3) and reduced glutathione (GSH) peptide on purified ACE were researched. Nicotinamide and GSH peptide on purified ACE showed an inhibition effect. IC50 values for nicotinamide and GSH were calculated as 14.3 μM and 7.3 μM, respectively. Type of inhibition and Ki values for nicotinamide and GSH from the Lineweaver-Burk graph were determined. The type of inhibition for nicotinamide and GSH was determined as non-competitive inhibition. Ki value was calculated as 15.4 μM for nicotinamide and 6.7 μM for GSH. Also, GSH peptide showed higher inhibitory activity on ACE activity than nicotinamide. In this study, it was concluded that nicotinamide and GSH peptide compounds, which show an inhibition effect on ACE activity, may have both protective and therapeutic effects against hypertension.