Synthesis and solution conformation of c(D-Trp-D-Cys(SO3-Na+)-Pro-D-Val-Leu), a potent endothelin-A receptor antagonist.

The endothelin family of polypeptides are known to exert potent physiological effects which include cardiovascular regulation. The solution conformation and dynamics of c(D-Trp-D-Cys(SO3-Na+)-Pro-D-Val-Leu), a potent endothelin-A receptor-selective antagonist, were characterized in aqueous solution by NMR spectroscopy and molecular modeling. NMR-derived conformational constraints were combined with computer-assisted molecular modeling using distance geometry calculations and energy minimization. The pentapeptide backbone is shown to adopt a single conformation in solution comprising a type II beta-turn and an inverse gamma-turn, with each residue in the trans conformation. Molecular dynamics were explored using relaxation measurements and low-temperature studies, and indicate that the peptide backbone is highly constrained with little conformational mobility present.