H-Tyr-Thr-Asp-Glu-Cys-Glu-Leu-Cys-Ile-Asn-Val-Ala-Cys-Thr-Gly-Cys-OH (Disulfide bonds between Cys⁴ and Cys¹²/Cys⁷ and Cys¹⁵)