title: Formation of liquid crystalline phase of actin filament solutions and its dependence on filament length as studied by optical birefringence.
abstract: We studied the formation and structure of liquid crystalline phase of F-actin solutions by polarized light photometry, assuming that a small domain of the liquid crystalline phase works as a linear retardation plate. Transmittance of polarized light due to the birefringence of liquid crystalline phase appeared above a threshold concentration of F-actin. The threshold increased with a decrease in filament length, which was regulated by calcium-activated gelsolin. The intensity increased linearly with increasing concentrations until it reached a stationary value. The deviation of optical axis direction of the putative retardation plate was estimated 7-15 degrees. These results indicate that:(a) the liquid crystalline phase is formed above a threshold concentration of F-actin; (b) the threshold is proportional to the inverse of filament length; (c) the ordered phase coexists with the isotropic one, increasing the volume fraction with increasing concentrations until all filaments take the liquid crystalline structure; (d) the filaments in liquid crystalline phase take a highly ordered array. These results can be attributed to the excluded volume effect of rod-like molecules on the formation of liquid crystalline structure.
authors.affiliation: Department of Biophysics, Kyoto University, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Suzuki
authors.forename: T
authors.initials: T
authors.lastname: Maeda
authors.forename: T
authors.initials: T
authors.lastname: Ito
mesh_terms: D008841:Actin Cytoskeleton / Q000648:ultrastructure; D000199:Actins / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D001718:Birefringence; D007700:Kinetics; D008433:Mathematics; D008859:Microscopy, Polarization; D008962:Models, Theoretical; D009132:Muscles / Q000378:metabolism; D011817:Rabbits; D012996:Solutions
chemical_list: D000199:Actins; D012996:Solutions