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Protein Short-Time Diffusion in a Naturally Crowded Environment.

Protein Short-Time Diffusion in a Naturally Crowded Environment. Thumbnail


Abstract

The interior of living cells is a dense and polydisperse suspension of macromolecules. Such a complex system challenges an understanding in terms of colloidal suspensions. As a fundamental test we employ neutron spectroscopy to measure the diffusion of tracer proteins (immunoglobulins) in a cell-like environment (cell lysate) with explicit control over crowding conditions. In combination with Stokesian dynamics simulation, we address protein diffusion on nanosecond time scales where hydrodynamic interactions dominate over negligible protein collisions. We successfully link the experimental results on these complex, flexible molecules with coarse-grained simulations providing a consistent understanding by colloid theories. Both experiments and simulations show that tracers in polydisperse solutions close to the effective particle radius Reff = ? Ri3?1/3 diffuse approximately as if the suspension was monodisperse. The simulations further show that macromolecules of sizes R > Reff ( R < Reff) are slowed more (less) effectively even at nanosecond time scales, which is highly relevant for a quantitative understanding of cellular processes.

Acceptance Date Mar 21, 2019
Publication Date Apr 18, 2019
Publicly Available Date Mar 29, 2024
Journal Journal of Physical Chemistry Letters
Print ISSN 1948-7185
Publisher American Chemical Society
Pages 1709 - 1715
DOI https://doi.org/10.1021/acs.jpclett.9b00345
Publisher URL https://pubs.acs.org/doi/10.1021/acs.jpclett.9b00345

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