The conformation of gramicidin A in dimethylsulphoxide solution. A full analysis of the one- and two-dimensional 1H, 13C, and 15N nuclear-magnetic-resonance spectra.

摘要: The combined application of one- and two-dimensional high-field NMR techniques has led to the first assignment 1H, 13C, 15N spectra pentadecapeptide gramicidin A in dimethylsulphoxide solution. 62.9-MHz 100.6-MHz 13C spin-lattice relaxation times 13C-[1H] NOE factors for backbone alpha carbons have been analysed 'model-free' approach give a single correlation time (tau m) isotropic overall molecular motion an order parameter internal each C H group backbone. relatively high constant values along indicate degree ordering structure, while show that motions are progressively more rapid towards N terminus. average vicinal HNC couplings 7.4 Hz 8.4 respectively alternate L- D-amino acid residues. not consistent with either ribbon conformation or right-handed beta 6.3 helix; they model proposed by Glickson et al. [Glickson, J. D., Mayers, D. F., Settine, M. & Urry, W. (1972) Biochemistry 11, 477-486] which there is conformational equilibrium disorder equilibrium, ordered structure being left-handed helix disordered state having local random-coil character.