| Abstract: | The fractions obtained from the partially hydrolyzed branched Streptococcus salivarius levan were examined in solution. Sedimentation coefficients, S0, intrinsic viscosities, [η], weight-average molecular weights, M w, and radii of gyration were obtained from sedimentation velocity, viscosity, and light-scattering measurements. Double logarithmic plots of [η] vs M w and S0 vs M w each yielded two linear segments intersecting at M w ≈ 105. Hydrodynamic data suggest that fractions of M w > 105 behave as compact spheres, whereas for M w < 105, the particles are best characterized as linear random coils. Calculations based on theories of random coils and spheres support the above observations. |
