The concentration dependence of sedimentation for polysaccharides

The relationship between the sedimentation co-efficient s(0) and its concentration coefficient k(S) obtained in experiments on velocity sedimentation for polysaccharides is discussed. The values of s(0), k(S) and an independently determined molecular weight reported by different authors for different polysaccharides are considered. It was established that the scaling relation, k(S) similar to s(0)(nu) unambiguously relates to the scaling relation s(0) similar to M-b. The values of the sedimentation parameter beta(S) introduced on the basis of Svedberg's equation for s(0) and on the basis of the expression k(S) = B[h(2)]M-3/2(-1) are discussed and the generalized Wales-van Holde-Rowe equation M-KS = (N-A/beta(S))(3/2)[s](3/2) k(S)(1/2) is used for evaluation of the molecular weights of polysaccharides. The adequacy of this evaluation is illustrated by taking as an example the determination of the unit length weight of an extra-rigid polysaccharide chain and of the equilibrium rigidity of rigid-chain, semi-rigid-chain and flexible-chain polysaccharides. The pair of experimental values s(0) and k(S) obtained in a single series of experiments give the same information as may be obtained from the other pairs of hydrodynamic values such as [eta] and s(0) or [eta] and D-0, where [eta] is the intrinsic viscosity and D-0 is the translational diffusion coefficient.