[Phe21]big endothelin‐1(18–34) and [Ala31]big endothelin‐1(18–34) inhibit the human endothelin‐converting enzyme‐1 (ECE‐1) expressed in CHO‐K1 cells in a different fashion

摘要

>Endothelin-converting enzyme-1 (ECE-1) is one of the most important enzymes to convert big endothelin-1 (big ET-1) to ET-1. To identify the inhibitors of 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, [Phe21]big ET-1(18–34) and [Ala31]big ET-1(18–34) exhibited a significant inhibition of ECE-1. A kinetic analysis revealed [Phe21]big ET-1(18–34) to be a competitive inhibitor (K _i=20.6 μM) and [Ala31]big ET-1(18–34) to be a non-competitive inhibitor (K _i=35.6 μM). These results not only support the concept that ECE-1 recognizes big ET-1 both at the P1 position and at the C-terminal region but also revealed that these two regions are recognized by this enzyme in a different manner.