Structure of the proteolipid protein extracted from bovine central nervous system myelin with nondenaturing detergents.
As a basis for attempts to define the structures of the proteins within myelin, methods have been developed for their extraction and isolation in solutions of non-denaturing detergents. With use of solutions of deoxycholate or Triton X-100, up to 90% of the protein has been extracted from bovine CNS myelin, along with most of the phospholipid. The proteolipid protein has been purified in deoxycholate solutions by chromatography on a blue dye-ligand column, which retained all of the basic protein and 2',3'-cyclic nucleotide-3'-phosphodiesterase, and then on Sephacryl S300, which separated proteolipid protein from phospholipid and high-molecular-weight proteins. The proteolipid protein was isolated from Triton X-100 extracts of myelin by adsorption onto phosphocellulose resin, with subsequent elution by 0.5 M sodium chloride. Gel permeation chromatography was used as the final purification step. Sedimentation equilibrium experiments gave a monomer molecular weight of 134,000 +/- 8000 in deoxycholate and 145,000 +/- 17,000 in Triton X-100 solutions. On the basis of an apparent subunit molecular weight of 23,500 it was deduced that the native protein is probably hexameric. Above 0.2 gL-1 in Triton X-100 solutions and 0.5 gL-1 in deoxycholate solutions the protein aggregated. In deoxycholate solutions the protein adopts the highly helical conformation expected for an intrinsic membrane protein.
D000818:Animals; D001923:Brain Chemistry; D002417:Cattle; D002942:Circular Dichroism; D003840:Deoxycholic Acid; D003902:Detergents; D004591:Electrophoresis, Polyacrylamide Gel; D009185:Myelin Proteins / Q000302:isolation & purification*; D018991:Myelin Proteolipid Protein; D009186:Myelin Sheath / Q000032:analysis*; D017830:Octoxynol; D011092:Polyethylene Glycols
D003902:Detergents; D009185:Myelin Proteins; D018991:Myelin Proteolipid Protein; D003840:Deoxycholic Acid; D011092:Polyethylene Glycols; D017830:Octoxynol