Sensitivity improvement for correlations involving arginine side-chain Nε/Hε resonances in multi-dimensional NMR experiments using broadband 15N 180° pulses

Junji Iwahara, G. Marius Clore

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Due to practical limitations in available 15N rf field strength, imperfections in 15N 180° pulses arising from off-resonance effects can result in significant sensitivity loss, even if the chemical shift offset is relatively small. Indeed, in multi-dimensional NMR experiments optimized for protein backbone amide groups, cross-peaks arising from the Arg guanidino 15N (∼85 ppm) are highly attenuated by the presence of multiple INEPT transfer steps. To improve the sensitivity for correlations involving Arg NεHε groups, we have incorporated 15N broadband 180° pulses into 3D 15N-separated NOE-HSQC and HNCACB experiments. Two 15N-WURST pulses incorporated at the INEPT transfer steps of the 3D 15N-separated NOE-HSQC pulse sequence resulted in a ∼1.5-fold increase in sensitivity for the Arg NεHε signals at 800 MHz. For the 3D HNCACB experiment, five 15N Abramovich-Vega pulses were incorporated for broadband inversion and refocusing, and the sensitivity of Arg1 Hε-15Nε-13Cγ/13Cδ correlation peaks was enhanced by a factor of ∼1.7 at 500 MHz. These experiments eliminate the necessity for additional experiments to assign Arg 1Hε and 15Nε resonances. In addition, the increased sensitivity afforded for the detection of NOE cross-peaks involving correlations with the 15 Nε/1Hε of Arg in 3D 15N-separated NOE experiments should prove to be very useful for structural analysis of interactions involving Arg side-chains.

Original languageEnglish (US)
Pages (from-to)251-257
Number of pages7
JournalJournal of Biomolecular NMR
Volume36
Issue number4
DOIs
StatePublished - Dec 1 2006
Externally publishedYes

Keywords

  • Arginine guanidino group
  • BroadbandN 180 pulse
  • Off-resonance
  • Pulse imperfection
  • Sensitivity improvement

ASJC Scopus subject areas

  • Biochemistry
  • Spectroscopy

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