CIRCULAR DICHROIC ANALYSIS OF THE SECONDARY STRUCTURE OF MYELIN BASIC-PROTEIN AND DERIVED PEPTIDES BOUND TO DETERGENTS AND TO LIPID VESICLES

In aqueous solution bovine myelin basic protein exhibits no significant α-helical or β-pleated sheet structure. However, in vivo this protein is associated largely with the myelin membrane: experiments have therefore been performed to determine the structure of the protein when bound to lipid bilayers. Circular dichroism spectra show that this protein undergoes a major conformational change on binding to lipid bilayer vesicles formed from diacylphosphatidylserine or diacylphosphatidic acid, and on binding to micelles of several detergents. Association with diacylphosphatidylcholine failed to induce a structural change: this observation is interpreted in terms of an earlier report that lysophosphatidylcholine does increase the α-helical content of basic protein. These circular dichroism measurements and studies of the binding to the bilayer-forming lipids appear to provide support for significant hydrophobic lipid-protein interactions. Similar studies using two peptides produced by cleavage of the phenylalanine-phenylalanine bond between residues 89 and 90 of basic protein indicate that a major structure-forming region in the middle of the protein has been disrupted by this scission. © 1979.