Endothelins are endothelium-derived vasoconstrictor peptides. Endothelin-1 is expressed as a 212-aa precursor (preproendothelin-1) that is sequentially cleaved into 2 chains: Endothelin-1 (21 aa) and Big Endothelin-1 (38 aa). Big endothelin-1 is cleaved to yield endothelin-1 via the activity of an endothelin-converting enzyme (ECE). Big Endothelin-1 can be hydrolyzed by chymase to generate endothelin 1 (1-21) in vitro.Human: H-Cys-Ser-Cys-Ser-Ser-Leu-Met-Asp-Lys-Glu-Cys-Val-Tyr-Phe-Cys-His-Leu-Asp-Ile-Ile-Trp-Val-Asn-Thr-Pro-Glu-His-Val-Val-Pro-Tyr-Gly-Leu-Gly-Ser-Pro-Arg-Ser-OH (Cys1-Cys15, Cys3-Cys11) or H-CSCSSLMDKECVYFCHLDIIWVNTPEHVVPYGLGSPRS-OH (Cys1-Cys15, Cys3-Cys11)