Structure of tyrocidine micelles in isotropic aqueous solution.
Aqueous solutions of tyrocidine B, iodoacetyltyrocidine B, and diiodotyrocidine B in 40% H2O:60% ethanol (w/w) were investigated by analytical ultracentrifugation, light scattering, and small-angle X-ray scattering techniques. A reasonable hydrodynamic description of the aggregates of molecular weight 28,600 is a rod with a length of 170 A and a diameter of 30 A; this description is consistent with the X-ray scattering data. Over a broad range of concentrations, inelastic light scattering measurements and small-angle X-ray scattering experiments provide the same hydrodynamic values (e.g., Stokes radii and frictional ratios). The positions of the iodines were resolved and found at a radius (R) of 16 A. So, the iodine-iodine distance across the cross section is 34 A, indicating that labeled tyrocidine B is not affected during the aggregational process.
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Märkische Fachhochschule, Department of Biotechnology and Physical Chemistry, Iserlohn, West Germany.
D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002850:Chromatography, Gel; D008027:Light; D008823:Micelles; D008970:Molecular Weight; D012542:Scattering, Radiation; D012996:Solutions; D013696:Temperature; D014440:Tyrocidine / Q000032:analysis*; D014449:Tyrothricin / Q000032:analysis*; D014461:Ultracentrifugation; D014783:Viscosity; D014965:X-Rays
D008823:Micelles; D012996:Solutions; D014440:Tyrocidine; D014449:Tyrothricin