Property of kinin-forming enzyme in rat stomach

The effects of inhibitors on the kinin-forming enzyme (KFE) activity in the rat stomach were investigated at pH 4.8. The KFE activity was unaffected by trasylol (200 KIU/ml), soybean trypsin inhibitor (100 microgram/ml) and p-tosyl-L-lysine-chloromethyl ketone (10-3 M), but was inhibited by pepstatin A (10(-6) M) and chymostatin (1.5 x 10(-4) M). Each product from the rat plasma kininogen by the rat stomach KFE and the bovine spleen cathepsin D was eluated at the same retention time on the equilibrium chromatography on the SP-Sephadex C-25 column. The KFE activity in the rat stomach was considerably high compared with that in various regions of the intestine. These results suggest that the KFE is characteristically similar to cathepsin D, and the enzyme is probably relevant to the function of the stomach.