Hydration and bulk solvent fluctuations drive protein fluctuations

Biological Physics Seminar - Fall 2009

"Hydration and bulk solvent fluctuations drive protein fluctuations"
Robert Young
Northern Arizona University
Date: Wednesday, November 18, 2009
Location: Biodesign B105
Time: 4:00 - 5:00 pm
Host: Dmitry Matyushov
Proteins have a hydration shell and exist in a bulk solvent. We propose distinct roles for the hydration water and the bulk solvent: 1) internal protein fluctuations are slaved to fluctuations of the hydration water; 2) large scale protein fluctuations are slaved to fluctuations of the bulk solvent. Experimental results for hydration effects on myoglobin from a broad range of tools – broadband dielectric relaxation spectroscopy, Mossbauer effect, incoherent neutron scattering, ligand binding, and transient optical spectroscopy – are given a unified explanation by our model. We extend the applications to incoherent neutron scattering data for the mean-square displacement of other hydrated protein powder samples including maltose binding protein. We have also extended the model to include effects of bulk solvent on large-scale protein fluctuations: for example, to the fluctuations of the functional cleft in dehydrated lysozyme in glycerol probed by dielectric spectroscopy, NMR, and incoherent neutron scattering. The results reinforce the concept that fluctuations of the bulk solvent drive large scale protein fluctuations. (07-13-2009. Revised 11-3-2009)


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