Alteration of lipid-phase behavior in multiple sclerosis myelin revealed by wide-angle x-ray diffraction

Abstract

Wide-angle x-ray diffraction studies revealed that the lipid-phase transition temperature of multiple sclerosis (MS) myelin was about 20°C lower than that of normal myelin, indicating differences in the physical organization of the bilayer. The transition of liposomes prepared from total lipid extracts of normal myelin was 12°C lower than that for corresponding intact myelin, demonstrating that the protein of normal myelin had a substantial ordering effect on the lipid bilayer. The transition temperature for liposomes of MS myelin lipid was essentially similar to that for isolated MS myelin. Because of protein/phospholipid ratio was higher in MS myelin, and no difference in degree of fatty acid saturation was observed, the inability of MS myelin protein to organize the lipid reflects a qualitative difference in the proteins.