The conformation studies of myelin P₂ protein and its peptides were carried out using circular dichroism spectroscopy. Circular dichroism spectra show that P₂ protein undergoes a major conformational change on binding to micelles formed from acidic phospholipids or acidic detergents. Association with zwitterionic phospholipids show much less conformational effects. Similar studies with large peptides derived from the P₂ protein show the same trends. The relationship of the conformation of the P₂ protein to the disease-inducing effects is described.