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Resistance to Disruption of Multilamellar Fragments of Central Nervous System Myelin
Author(s) -
Sedzik Jan,
Toews Arrel D.,
Blaurock Allen E.,
Morell Pierre
Publication year - 1984
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1984.tb05402.x
Subject(s) - myelin , bilayer , vesicle , chemistry , crystallography , sonication , biophysics , gel electrophoresis , diffraction , myelin basic protein , electron microscope , polyacrylamide gel electrophoresis , analytical chemistry (journal) , chromatography , biochemistry , membrane , biology , central nervous system , optics , enzyme , neuroscience , physics
Single‐bilayer vesicles of myelin are desirable for studying myelin development and metabolism. Accordingly, our interest was drawn to a procedure for ves‐iculating myelin (Steck et al., Biochim. Biophys. Acta 509, 397–408, 1978). We used X‐ray diffraction analysis to examine these putative vesicle preparations because much larger amounts of material can be surveyed by this method than by electron microscopy. The sharpness (width) of the rings in the X‐ray diffraction pattern varies inversely with the number of bilayers per multilayer structure. We therefore expected to see the diffuse diffraction pattern characteristic of single bilayers. Diffraction patterns were recorded from isolated rat brain myelin before and after the vesiculation procedure. Both patterns showed sharp rings, indicating numerous multilayered structures. Average values ranging from 7 to 10 bilayers per multilayer were calculated in both cases. This procedure did produce a small fraction of single‐bilayer structures, which were isolated by differential centnfu gation; however, these accounted for only about 1% of the total myelin present. The diffraction pattern of this material showed the diffuse band typical of single‐bilayer structures, and sodium dodecyl sulfate‐polyacrylamide gel electrophoresis indicated it had the same protein composition as in normal myelin. Similar results were also obtained using either fresh or frozen bovine brain myelin. Variations of the published vesiculation procedure (incubation in 0.1 M NaCl or in buffers containing glycerol; disruption by sonication or use of a Tissumizer) also were not effective in breaking down the multilamellar fragments into thinner structures. We conclude that the multilamellar fragments of isolated CNS myelin resist disruption into single‐bilayer structures.