Pico- to nanosecond motions in protein side-chains explored by a combination of high-field NMR and high-resolution relaxometry

Abstract

The function of a protein is governed not only by its three-dimensional structure but also by its dynamics. NMR relaxation is a powerful technique to characterize such dynamics. Traditional measurements of relaxation rates at high fields provide valuable information but limited sampling of the spectral density function over narrow frequency ranges. Here, we use high-resolution relaxometry to obtain an extensive sampling of the spectral density function.

Over the past two decades, methyl groups have been shown to be a valuable probes of protein sidechain dynamics through the measurement of nuclear spin relaxation parameters.

CDNRates

We have first carried out a theoretical study of all the relaxation pathways as a function of the magnetic field. These calculations take into account the theoretical 839808 relaxation pathways and 9 interactions Hamiltonians

CDNRates

High-file relaxation rates were analyzed with the spectral density function J(omega). The order parameters S^2 = S_{cc}^2*S_f^2 are in good agreement with the order parameters obtained from deuterium relaxation by Wand and coworkers.

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