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

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• 作者：Junji Iwahara and G. Marius Clore
• 关键词：arginine guanidino group ; broadband 15N 180 pulse ; off ; resonance ; pulse imperfection ; sensitivity improvement
• 刊名：Journal of Biomolecular NMR
• 出版年：2006
• 出版时间：December, 2006
• 年：2006
• 卷：36
• 期：4
• 页码：251-257
• 全文大小：259 KB
• 刊物类别：Physics and Astronomy
• 刊物主题：Physics
  Biophysics and Biomedical Physics
  Polymer Sciences
  Biochemistry
  
• 出版者：Springer Netherlands
• ISSN：1573-5001

文摘

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 15Nε (~85 ppm) are highly attenuated by the presence of multiple INEPT transfer steps. To improve the sensitivity for correlations involving Arg Nε–Hε 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 Nε–Hε 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 Arg1Hε-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 15Nε/1Hε of Arg in 3D 15N-separated NOE experiments should prove to be very useful for structural analysis of interactions involving Arg side-chains.