Big endothelin analogues with inhibitory activity on endothelin-converting enzyme-1

Big endothelin-1 (big ET-1) is converted into an active form, ET-1, by endothelin-converting enzyme-1 (ECE-1). To assess the mechanism of substrate recognition by ECE-1, we examined the effects of variously substituted analogues of big ET-1 on ECE-1 activity, using solubilized membranes prepared from human ECE-1-expressed CHO-K1 cells. Among the big ET-1 analogues tested, [²¹Phe]big ET-1[18-34] and [³¹Ala]big ET-1[18-34] exhibited significant inhibition of ECE-1. A kinetic analysis revealed [²¹Phe]big ET-1[18-34] to be a competitive inhibitor (K_i = 21 μM) and [³¹Ala]big ET-1[18-34] to be a noncompetitive inhibitor (K_i = 36 μM). These results suggested that ECE-1 recognizes big ET-1 at the P1 position and the C-terminal region in a different manner and that modification of these regions can produce ECE-1 inhibitors.