Correlated dipolar and dihedral fluctuations in a protein

Abstract

Dihedral fluctuations are not directly amenable due to the limitation of the experimental probe. NMR experiments probe dipolar fluctuations given in terms of cross-correlated relaxation (CCR) rates, given by the zero frequency spectral density function of the fluctuations. Here, we calculate the zero frequency spectral function from molecular dynamics trajectories for dipolar and dihedral angle fluctuations and show that they are correlated. Thus, the CCR can be a marker of dihedral fluctuations.