Counterion diffusion in heparin solutions.

The physiological importance of heparin is due to its strong interaction with bivalent counterions, especially Ca2+. A diffusional approach of this property is presented in this article: the observable is the self-diffusion coefficient of the counterions, as a function of the ratio of the polyelectrolyte over the added salt concentrations. All the results are in agreement with a simple "quasi-chemical model" in which two different states are assumed for the counterions: "free" or "bound.

Conformational change of core particles studied by quasielastic light scattering.

The diffusion translational coefficient Dt of core particles in monodisperse solutions has been measured by the quasielastic light scattering method in a large scale of salinities over the range 6.10(-4) to 2M Na+ or K+. The observed values of DT are independent of particle concentration in the range 0.