NMR delineation of inner and outer protons from paramagnetic relaxation perturbations in 1 D and 2D spectra of peptides

Abstract

The use of soluble spin labels to filter out the cross-peaks of outer proton nuclei in 2D NMR spectra is proposed as a general method of obtaining structural information about complex molecules. Gramicidin S, a decapeptide of well defined and stable structure, has been used as a model system to correlate the paramagnetic effects observed in 1 D and 2D spectra and the peptide solution conformation. The method appears particularly suited to obtaining information about the hydrogen bonding of backbone amide protons.