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Biologische Systeme und Medizin Poster: Mi., 14:00–16:30 M-P188
Protein Diffusion in Biological Cells
Wolfgang Doster 1 , Sebastian Busch 1 , Stephane Longeville 2
1 Technical University Munich, Physics department E 13, D-85748 Garching – 2 LLB
CEA CRNS Saclay 91191, Gif-sur Yvette, France
A characteristic of the interior of cells is the high total concentration of macromolecules.
Such media are termed crowded rather than concentrated since no single
macromolecular species occurs at high concentration. But taken together they occupy
a signifcant fraction (20-30 %) of the total volume. This affects protein diffusion and
protein association equilibria through excluded volume effects (highly non-ideal solutions).
The goal of our project is to understand the effect of protein-protein interactions
on molecular diffusion at high concentration. Our model of crowding in biological cells
is hemoglobin diffusion inside erythrocytes. Using a combination of neutron spin echo
and backscattering spectroscopy with low angle scattering, we analyse the effects of
direct interactions and hydrodynamic interactions. Neutrons scattering allows probing
molecular diffusion on a microscopic scale at high Q. The protein diffusion coefficients
increase with decreasing Q indicating a cross-over from short-time self-diffusion to
collective diffusion. Myoglobin solutions were investigated at various protein concentrations
as well as hemoglobin diffusion in blood cells.