CONFORMATION OF A TETRADECAPEPTIDE EPITOP E OF MYELIN BASIC-PROTEIN

The peptide r-Gln-Lys-Arg-Pro-Ser-Gln-Arg-His-Gly-Ser-Lys-Tyr, which c omprises the first 14 residues of the acetylated N-terminus of myelin basic protein, is an epitopic site for two monoclonal antibodies to th e human protein. The conformations of the tetradecapeptide in aqueous solutions were investigated employing high-resolution H-1- and C-13-NM R spectroscopy. Two-dimensional techniques were used to assign the spe ctra observed from both nuclei. Nuclear-Overhauser-effect data, amide proton temperature coefficients,C-13 spin-lattice relaxation times, di stance geometry calculations and dynamic simulated annealing provided evidence that the solution conformations of the tetradecapeptide inclu ded a nascent a-helix in the N-terminal segment, and a loop extending from Ser7 to Ser12 that bring His10 and Tyr14 into close proximity.