Coupling between overall rotational diffusion and domain motions in proteins and its effect on dielectric spectra

Abstract

In this work, we formulate a closed-form solution of the model of a semirigid molecule for the case of fluctuating and reorienting molecular electric dipole moment. We illustrate with numeric calculations the impact of protein domain motions on dielectric spectra using the example of the 128 kDa protein dimer of Enzyme I. We demonstrate that the most drastic effect occurs for situations when the characteristic time of protein domain dynamics is comparable to the time of overall molecular rotational diffusion. We suggest that protein domain motions could be a possible explanation for the high-frequency contribution that accompanies the major relaxation dispersion peak in the dielectric spectra of protein aqueous solutions. We propose that the presented computational methodology could be used for the simultaneous analysis of dielectric spectroscopy and nuclear magnetic resonance data. Proteins 2015; 83:1571-1581. © 2015 Wiley Periodicals, Inc.

Spatio-temporal coordination among functional residues in protein

“…However, information provided by Pearson Correlations is far from complete. Macromolecular binding takes place typically by rotational diffusion ranging in timescales of tens of nano-seconds (ns)16, so that the binding surfaces are mutually exposed. This means that the changes at sites upon first ligand binding must affect the downstream binding sites till this time.…”