Converts big endothelin-1 to endothelin-1. Hydrolysis of the 21-Trp-|-Val-22 bond in big endothelin to form endothelin 1. Binds 1 zinc ion per subunit. Inhibited by phosphoramidon. Homodimer; disulfide-linked (PubMed:8645169). Interacts with PPP1R16B (By similarity). All isoforms are expressed in aortic endothelial cells. Isoform A is also expressed in liver; isoform B in smooth muscle cells and fibroblasts; isoform C in aortic endothelial cells, smooth muscle cells, fibroblasts, liver and lung, and isoform D in smooth muscle cells. Belongs to the peptidase M13 family.