DIPC Colloquium: Unexpected complexities of macromolecular diffusion in membranes and dense protein solutions
DIPC Seminars
- Speaker
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Gerhard Hummer, Max-Planck-Institut für Biophysik, Frankfurt, Germany
- When
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2019/09/19
18:00 - Place
- Donostia International Physics Center
- Add to calendar
-
iCal
Abstract: We studied the diffusion of proteins and other macromolecules in
dense and dilute solution, and in lipid membranes using molecular dynamics
simulations. In systems mimicking the interior of a living cell, with densely
packed proteins, translational and rotational diffusion of proteins slow down
dramatically at high protein concentrations, and the Stokes-Einstein relation
appears to break down.
Transient clustering of proteins is the underlying cause, explaining both the
resulting increase in the apparent Stokes radius and the rise in the viscosity
within the theoretical framework of attractive colloidal systems.
Overall, long simulation trajectories of large membrane, protein, and nucleic
acid systems give us a remarkably rich picture of macromolecular diffusion. In
concentrated systems, diffusion is hindered dramatically even by weak and
transient interactions; in membranes, diffusion appears to break down
entirely. However, hydrodynamic theory resolves these challenges and corrects
for the system-size dependencies, giving us diffusion coefficients that can be
interpreted meaningfully and compared to experiment.
[Gerhard Hummer](https://www.biophys.mpg.de/es/hummer.html) is Director of the
MPI for Biophysics in Frankfurt, where he leads the Department of Theoretical
Biophysics. He uses molecular simulations, modeling, and theory to study the
structure and dynamics of biological systems at the molecular level, in order
to elucidate their function. His current research focuses on molecular
principles in bioenergetics, membrane transport, and membrane remodeling.
Prof. Hummer is Fellow of the APS and has received, among other prizes, the
Raymond and Beverly Sackler International Prize in Biophysics.