Heteronuclear proton assisted recoupling
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DePaepe_JChemPhys_134_095101.pdf
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Author(s)
Paepe, Gael De
Lewandowski, Jozef R.
Loquet, Antoine
Eddy, Matthew Thomas
Megy, Simon
Bockmann, Anja
Griffin, Robert Guy
Date Issued
March 2011
Journal
Journal of Chemical Physics
Publisher
American Institute of Physics (AIP)
Citation
Paëpe, Gaël De et al. “Heteronuclear Proton Assisted Recoupling.” The Journal of Chemical Physics 134.9 (2011): 095101. © 2011 American Institute of Physics
Version
Final published version
Abstract
We describe a theoretical framework for understanding the heteronuclear version of the third spin assisted recoupling polarization transfer mechanism and demonstrate its potential for detecting long-distance intramolecular and intermolecular [superscript 15]N–[superscript 13]C contacts in biomolecular systems. The pulse sequence, proton assisted insensitive nuclei cross polarization (PAIN-CP) relies on a cross term between [superscript 1]H–[superscript 15]N and [superscript 1]H–[superscript 13]C dipolar couplings to mediate zero- and/or double-quantum [superscript 15]N–[superscript 13]C recoupling. In particular, using average Hamiltonian theory we derive effective Hamiltonians for PAIN-CP and show that the transfer is mediated by trilinear terms of the form N±C∓Hz (ZQ) or N±C±Hz (DQ) depending on the rf field strengths employed. We use analytical and numerical simulations to explain the structure of the PAIN-CP optimization maps and to delineate the appropriate matching conditions. We also detail the dependence of the PAIN-CP polarization transfer with respect to local molecular geometry and explain the observed reduction in dipolar truncation. In addition, we demonstrate the utility of PAIN-CP in structural studies with [superscript 15]N–[superscript 13]C spectra of two uniformly [superscript 13]C,[superscript 15]N labeled model microcrystalline proteins—GB1, a 56 amino acid peptide, and Crh, a 85 amino acid domain swapped dimer (MW = 2 × 10.4 kDa). The spectra acquired at high magic angle spinning frequencies (ω[subscript r]/2π > 20 kHz) and magnetic fields (ω[subscript 0H]/2π = 700–900 MHz) using moderate rf fields, yield multiple long-distance intramonomer and intermonomer [superscript 15]N–[superscript 13]C contacts. We use these distance restraints, in combination with the available x-ray structure as a homology model, to perform a calculation of the monomer subunit of the Crh protein.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
Francis Bitter Magnet Laboratory (Massachusetts Institute of Technology)
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DOI of Published Version
https://doi.org/10.1063/1.3541251
