DETERMINATION OF AN 8-ANGSTROM INTERATOMIC DISTANCE IN A HELICAL PEPTIDE BY SOLID-STATE NMR-SPECTROSCOPY

The combination of transferred-echo double resonance (TEDOR) with rotational-echo double resonance (REDOR) has been used to measure an 8-angstrom fluorine-carbon internuclear distance in a nine-residue fragment of the peptide antibiotic emerimicin. The fragment is (FCH2CO-Phe-MeA-MeA-[1-C-13]MeA-[N-15]Val-Gly-Leu-MeA-MeA-OBzl)-F-19 (MeA = alpha-methylalanine or aminoisobutyric acid). The TEDOR part of this magic-angle-spinning, solid-state NMR experiment selects the C-13 label by its dipolar coupling to N-15 and suppresses the natural-abundance carbon background. The REDOR part of the experiment measures dipolar coupling of the selected carbon to F-19. The TEDOR-REDOR combined experiment works with a variety of spin 1/2 nuclei and can be used to characterize internuclear distances and geometry in macromolecular aggregates that do not crystallize.