Determination of the structure of [Nle7]-endothelin by 1H NMR

[Nle7]-endothelin was synthesized and studied by 1H NMR and distance geometry calculations. The NMR study was performed first in DMSO-d6 and then in 50% acetonitrile/water since this peptide aggregates in pure water. In both cases, all spin systems were identified and assigned with the aid of two-dimensional spectroscopy (2D): COSY (for scalar couplings) and NOESY (for dipolar couplings). On the basis of the acetonitrile/water NMR parameters, and using the DISGEO program, a three-dimensional structure of [Nle7]-endothelin is proposed and discussed.