title: Multiple-step method for making exceptionally well-oriented liquid-crystalline sols of macromolecular assemblies.
abstract: X-ray fiber diffraction is potentially powerful in solving the atomic structure of filamentous assemblies of macromolecules, as demonstrated for tobacco mosaic virus. However, it requires extremely well-oriented sols to allow for extraction of intensities on closely located layer-lines. A high degree of orientation requires a high filament concentration to restrain the orientational freedom, but orienting concentrated sols is hampered by their high viscosity. Here, we report a systematic method that reproducibly produces extremely good orientation, which involves three steps; liquid crystallization, centrifugation and magnetic orientation. We found that a slow centrifugation can trigger a dynamic self-orientation process to form perfectly homogeneous liquid-crystalline sols, and further centrifugation to concentrate sols followed by magnetic orientation produces exceptionally well-oriented sols. The best-oriented flagellar sol showed a disorientation angle of 0.6 degrees as 1sigma of its Gaussian distribution. The new method has been successfully applied to many other systems, such as tobacco mosaic virus and F-actin.
authors.affiliation: International Institute for Advanced Research, Matsushita Electric Industrial Co., Ltd, 3-4 Hikaridai, Seika, 619-02, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Yamashita
authors.forename: H
authors.initials: H
authors.lastname: Suzuki
authors.forename: K
authors.initials: K
authors.lastname: Namba
mesh_terms: D000199:Actins / Q000737:chemistry*; D003102:Colloids; D003460:Crystallization; D018360:Crystallography, X-Ray / Q000379:methods; D005407:Flagella / Q000737:chemistry / Q000648:ultrastructure; D005408:Flagellin / Q000737:chemistry* / Q000302:isolation & purification; D009994:Osmolar Concentration; D012486:Salmonella typhimurium; D012996:Solutions; D014027:Tobacco Mosaic Virus / Q000737:chemistry* / Q000648:ultrastructure
chemical_list: D000199:Actins; D003102:Colloids; D012996:Solutions; D005408:Flagellin