On the performance of spin diffusion NMR techniques in oriented solids: Prospects for resonance assignments and distance measurements from separated local field experiments

Nathaniel J. Traaseth, T. Gopinath, Gianluigi Veglia

Research output: Contribution to journalArticle

Abstract

NMR spin diffusion experiments have the potential to provide both resonance assignment and internuclear distances for protein structure determination in oriented solid-state NMR. In this paper, we compared the efficiencies of three spin diffusion experiments: proton-driven spin diffusion (PDSD), cross-relaxation-driven spin diffusion (CRDSD), and proton-mediated proton transfer (PMPT). As model systems for oriented proteins, we used single crystals of N-acetyl-L-15N-leucine (NAL) and N-acetyl-L-15N-valyl- L-15N-leucine (NAVL) to probe long and short distances, respectively. We demonstrate that, for short 15N/15N distances such as those found in NAVL (3.3 Å), the PDSD mechanism gives the most intense cross-peaks, while, for longer distances (>6.5 Å), the CRDSD and PMPT experiments are more efficient. The PDSD was highly inefficient for transferring magnetization across distances greater than 6.5 Å (NAL crystal sample), due to small 15N/15N dipolar couplings (<4.5 Hz). Interestingly, the mismatched Hartmann-Hahn condition present in the PMPT experiment gave more intense cross-peaks for lower 1H and 15N RF spinlock amplitudes (32 and 17 kHz, respectively) rather than higher values (55 and 50 kHz), suggesting a more complex magnetization transfer mechanism. Numerical simulations are in good agreement with the experimental findings, suggesting a combined PMPT and CRDSD effect. We conclude that, in order to assign SLF spectra and measure shortand long-range distances, the combined use of homonuclear correlation spectra, such as the ones surveyed in this work, are necessary.

Original languageEnglish (US)
Pages (from-to)13872-13880
Number of pages9
JournalJournal of Physical Chemistry B
Volume114
Issue number43
DOIs
StatePublished - Nov 4 2010

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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