AUTHOR=Franks W. Trent , Tatman Ben P. , Trenouth Jonah , Lewandowski Józef R. 

TITLE=Dipolar Order Parameters in Large Systems With Fast Spinning

JOURNAL=Frontiers in Molecular Biosciences

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/molecular-biosciences/articles/10.3389/fmolb.2021.791026

DOI=10.3389/fmolb.2021.791026

ISSN=2296-889X

ABSTRACT=<p>Order parameters are a useful tool for quantifying amplitudes of molecular motions. Here we measure dipolar order parameters by recoupling heteronuclear dipole-dipole couplings under fast spinning. We apply symmetry based recoupling methods to samples spinning under magic angle at 60 kHz by employing a variable flip angle compound inversion pulse. We validate the methods by measuring site-specific <sup>15</sup>N-<sup>1</sup>H order parameters of a microcrystalline protein over a small temperature range and the same protein in a large, precipitated complex with antibody. The measurements of the order parameters in the complex are consistent with the observed protein undergoing overall motion within the assembly.</p>