Protein Short-Time Diffusion in a Naturally Crowded Environment

Research output: Contribution to journalArticle


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 R eff = R i 3 1/3 diffuse approximately as if the suspension was monodisperse. The simulations further show that macromolecules of sizes R > R eff (R < R eff ) are slowed more (less) effectively even at nanosecond time scales, which is highly relevant for a quantitative understanding of cellular processes.


  • Marco Grimaldo
  • Hender Lopez
  • Christian Beck
  • Felix Roosen-Runge
  • Martine Moulin
  • Juliette M. Devos
  • Valerie Laux
  • Michael Härtlein
  • Stefano Da Vela
  • Ralf Schweins
  • Alessandro Mariani
  • Fajun Zhang
  • Jean Louis Barrat
  • Martin Oettel
  • V. Trevor Forsyth
  • Tilo Seydel
  • Frank Schreiber
External organisations
  • Institut Laue Langevin
  • European Synchrotron Radiation Facility
  • Keele University
  • University of Tübingen
  • Laboratoire Interdisciplinaire de Physique
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Biophysics
Original languageEnglish
Pages (from-to)1709-1715
Number of pages7
JournalJournal of Physical Chemistry Letters
Issue number8
Publication statusPublished - 2019 Apr 18
Publication categoryResearch