Partial alignment and measurement of residual dipolar couplings of proteins under high hydrostatic pressure
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High-pressure NMR spectroscopy has emerged as a complementary approach for investigating various structural and thermodynamic properties of macromolecules. Noticeably absent from the array of experimental restraints that have been employed to characterize protein structures at high hydrostatic pressure is the residual dipolar coupling, which requires the partial alignment of the macromolecule of interest. Here we examine five alignment media that are commonly used at ambient pressure for this purpose. We find that the spontaneous alignment of Pf1 phage, d(GpG) and a C12E5/n-hexnanol mixture in a magnetic field is preserved under high hydrostatic pressure. However, DMPC/DHPC bicelles and collagen gel are found to be unsuitable. Evidence is presented to demonstrate that pressure-induced structural changes can be identified using the residual dipolar coupling.
KeywordsResidual dipolar coupling High hydrostatic pressure Alignment media NMR spectroscopy Structure calculation
This work was supported by the National Institutes of Health (NIH) grant GM 102447. We thank Dr. Kathleen G. Valentine for helpful discussion.
Conflict of interest
A. J. W. declares a competing financial interest as Member of Daedalus Innovations, LLC, a manufacturer of high-pressure and reverse micelle NMR apparatus.
A. J. W. declares that the experiments comply with the current laws of U.S.A.
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