1H-nuclear magnetic resonance study of the association of the basic protein of central nervous system myelin with lysophosphatidylcholine

Abstract

High-resolution 270 MHZ 1H-nuclear magnetic resonance spectroscopy has been used to follow the interaction of myristoyllysophosphatidylcholine with bovine myelin basic protein. At lipid/protein ratios up to 30:1 it proved possible to follow changes in the spectra of both the protein and the lipid. Lysophosphatidylcholine induced several changes in the protein spectrum. Foremost amongst these changes were downfield shifts of histidine C2 protons, and upfield shifts and broadening of the phenylalanine aromatic proteins. Several other resonances assigned to nonpolar amino acid side chains also broadened. But even at a lipid/protein molar ratio of 30:1 the majority of the protein appeared to remain in a loosely coiled conformation. In the presence of the protein the lipid acyl chain peaks were moved upfield and broadened, whereas the resonances associated with the head-group protons were unaffected. These changes were consistent with partial immobilization of the acyl chain of lysophosphatidylcholine on binding to the basic protein, with hydrophobic interactions providing the predominant attraction between this lipid and the basic protein.