Diffusion of globular proteins in a Sephadex G200 gel bead

Abstract
We measured FRAP curves of solutions of globular proteins fractions labeled with fluorescein and included in a Sephadex G 200 single gel bead. We determined the diffusion coefficient D of these macromolecules in the gel. The measurement of the partition coefficient of these labeled macromolecules showed that fluorescein residues can induce a partial adsorption of the macromolecules on the gel matrix. When corrected for this effect, the reduced coefficient of diffusion D/D₀, (where D₀ is the diffusion coefficient in the free solution), was found higher than the value predicted by the Ogston et al. theory (Proc. Roy. Soc. A333 (1973) 297). This discrepancy was ascribed to the dynamic flexibility of the Sephadex gel matrix.