N.m.r. studies of myelin basic protein. Conformation of a peptide that is an antigenic determinant for B-cell reactivity

Abstract

The peptide Gly-Arg-Ala-Ser-Asp-Tyr-Lys-Ser, derived from myelin basic protein (MBP), is part of an epitope to monoclonal antibodies to human MBP. Its conformation has been studied in aqueous solution by high-resolution one- and two-dimensional 1H and 13C n.m.r. Two-dimensional correlated spectroscopy, pH titrations and one-dimensional spin-decoupling techniques were employed to assign the spectra observed from both nuclei. Amide proton temperature coefficients, coupling constants, 13C spin-lattice relaxation times and nuclear-Overhauser-effect data provide evidence that the solution conformations of the octapeptide include a type-II beta-turn with a hydrogen bond between the CO group of Arg2 and the NH group of Asp5. The results are discussed in view of a possible conformation of the antibody receptor site.