STRUCTURE DETERMINATION OF AN IMMUNOPOTENTIATOR PEPTIDE, CINNAMYCIN, COMPLEXED WITH LYSOPHOSPHATIDYLETHANOLAMINE BY H-1-NMR

The three-dimensional structure of a complex of cinnamycin, a 19-amino acid residue immunopotentiator peptide, and lysophosphatidylethanolam ine was determined by H-1-NMR. The complex was cylindrical in shape, 1 1 Angstrom in diameter and 26 Angstrom in length, excluding the acyl c hain of the phospholipid. The peptide had a hydrophobic pocket surroun ded by residues Phe-7 through Ala(S)-14 to bind to the head group of t he ligand. Fitting of the head group to the hydrophobic pocket was so good that other than a glycerophosphoethanolamine head group would be unable to fit the pocket. The goodness of the fitting is compatible wi th the strict specificity of ligand binding of the peptide.