N.M.R. studies of myelin basic protein. VII. Concentration and temperature dependence of amide resonances of the guinea pig encephalitogen in dimethyl sulfoxide

Abstract

The encephalitogenic peptide comprising residues 114-122 in human myelin basic protein, Phe-Ser-Trp-Gly-Ala-Glu-Gly-Gln-Arg, has been studied by proton magnetic resonance at 400 MHz in dimethyl sulfoxide solutions. Temperature coefficients of the chemical shifts of the amide resonances of Glu⁶, Gly⁷ and Arg⁹ have low values indicative of shielding from solvent. These data and nuclear Overhauser enhancements between protons widely separated in the primary structure suggest a compact structure for the peptide in dimethyl sulfoxide, probably associated with a reverse turn about the Gly⁴Ala⁵ residues. In freshly prepared solutions in the concentration range 0.20-5.0 mM, effects of intermolecular aggregation are not observed, but such aggregation may occur under other conditions.