Diffusion and microstructural properties of solutions of charged nanosized proteins: Experiment versus theory

GAPINSKI, J.; WILK, A.; PATKOWSKI, A.; HÄUSSLER, W.; BANCHIO, A. J.; PECORA, R.; NÄGELE, G.

JOURNAL OF CHEMICAL PHYSICS

Año: 2005 vol. 123 p. 5470 - 5470

0021-9606

We have reanalyzed our former static small-angle x-ray scattering and photon correlationspectroscopy results on dense solutions of charged spherical apoferritin proteins using theories recently developed for studies of colloids. The static structure factors S(q), and the small-wave-number collective diffusion coefficient Dc determined from those experiments are interpreted now in terms of a theoretical scheme based on a Derjaguin-Landau-Verwey-Overbeek-type continuum model of charged colloidal spheres. This scheme accounts, in anapproximate way, for many-body hydrodynamic interactions. Stokesian dynamics computersimulations of the hydrodynamic function have been performed for the first time for densecharge-stabilized dispersions to assess the accuracy of the theoretical scheme. We show that the continuum model allows for a consistent description of all experimental results, and that the effective particle charge is dependent upon the protein concentration relative to the added salt concentration. In addition, we discuss the consequences of small ions dynamics for the collective protein diffusion within the framework of the coupled-mode theory. © 2005 American Institute of Physics.