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 (By similarity). Interacts with PPP1R16B (PubMed:26806547). Belongs to the peptidase M13 family.