Speaker
Dr
Marco Grimaldo
(ILL)
Description
Approximately 10-40% of the intra- and extracellular fluids of living organisms are occupied by macromolecules such as proteins. This macromolecular crowding condition was shown to influence reaction rates, and to lead to anomalous diffusion. The study of protein diffusion in such a crowded environment is, generally, not an easy task. Nevertheless, neutron backscattering (NBS) is well suited for measurements of the short-time self-diffusion of proteins in highly concentrated aqueous (D2O) solutions [1-4]. We present a NBS study on the pico- to nanosecond self-diffusion of the antibody proteins immunoglobulins (Ig) in aqueous environment. To systematically investigate the effect of macromolecular crowding on protein dynamics we vary the concentration of cellular lysate, mimicking a cellular environment. The dynamics of Ig in lysate is then compared with that of Ig in pure (heavy) water as a function of its own concentration (self-crowding) [2]. Despite the high polydispersity and the not easily predictable variance in lysate composition, the measured diffusion of Ig as a function of the overall volume fraction are in rather good agreement with those of Ig in the self-crowded environment at comparable volume fraction, suggesting a crucial role of hydrodynamic interactions and hence, in principle, the applicability of colloidal theories to model the protein short-time diffusion even in a cell-like environment.
[1] Roosen-Runge F., Hennig M., Zhang F., Jacobs R.M.J., Sztucki M., Schober H., Seydel T., and Schreiber F. PNAS 108.29 (2011): 11815
[2] Grimaldo M., Roosen-Runge F., Zhang F., Seydel T., Schreiber F. JPCB 118.25 (2014): 7203.
[3] Grimaldo M., Roosen-Runge F., Hennig M., Zanini F., Zhang F., Zamponi, M., Jalarvo N., Schreiber F., Seydel T. JPCL 6.13 (2015): 2577.
[4] Braun M.K., Grimaldo M., Roosen-Runge F., Hoffmann I., Czakkel O., Sztucki M., Zhang F., Schreiber F., and Seydel T., JPCL 8.12 (2017): 2590.
Primary authors
Mr
Christian Beck
(ILL)
Dr
Fajun Zhang
(IAP- Universität Tübingen, Tübingen, Germany)
Dr
Felix Roosen-Runge
(Division for Physical Chemistry, Lund University, Lund, Sweden)
Dr
Frank Schreiber
(IAP- Universität Tübingen, Tübingen, Germany)
Dr
Marco Grimaldo
(ILL)
Dr
Tilo Seydel
(ILL, Grenoble, France)
