Homonuclear decoupling for enhancing resolution and sensitivity in NOE and RDC measurements of peptides and proteins
Publication date: Available online 22 November 2013
Source:Journal of Magnetic Resonance
Author(s): Jinfa Ying , Julien Roche , Ad Bax
Application of band-selective homonuclear (BASH) 1H decoupling pulses during acquisition of the 1H free induction decay is shown to be an efficient procedure for removal of scalar and residual dipolar couplings between amide and aliphatic protons. BASH decoupling can be applied in both dimensions of a homonuclear 2D NMR experiment and is particularly useful for enhancing spectral resolution in the HN-H? region of NOESY spectra of peptides and proteins, which contain important information on the backbone torsion angles. The method then also prevents generation of zero quantum and HN z-H? z terms, thereby facilitating analysis of intraresidue interactions. Application to the NOESY spectrum of a hexapeptide fragment of the intrinsically disordered protein ?-synuclein highlights the considerable diffusion anisotropy present in linear peptides. Removal of residual dipolar couplings between HN and aliphatic protons in weakly aligned proteins increases resolution in the 1H-15N HSQC region of the spectrum and allows measurement of RDCs in samples that are relatively strongly aligned. The approach is demonstrated for measurement of RDCs in protonated 15N/13C-enriched ubiquitin, aligned in Pf1, yielding improved fitting to the ubiquitin structure.
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