Homonuclear decoupling for enhancing resolution and sensitivity in NOE and RDC measurements of peptides and proteins

• Published in: Journal of magnetic resonance (1997) Vol. 241; pp. 97 - 102
• Main Authors: Ying, Jinfa, Roche, Julien, Bax, Ad
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2014
• Subjects: Animals; Anisotropy; Diffusion anisotropy; Humans; IDP; Liquid crystal; Liquid Crystals - chemistry; NOESY; Nuclear Magnetic Resonance, Biomolecular - methods; Protein Conformation; Proteins - chemistry; RDC; Residual dipolar coupling; Synuclein; Ubiquitin; Weak alignment; RDC; Ubiquitin; Residual dipolar coupling; IDP; Liquid crystal; NOESY; Diffusion anisotropy; Synuclein; Weak alignment
• ISSN: 1090-7807; 1096-0856
• DOI: 10.1016/j.jmr.2013.11.006

•Decoupling of HN–Hα interactions in peptides and proteins enhances resolution.•Decoupling removes zero quantum contributions to NOESY cross peaks.•Improved NOESY spectral resolution reveals considerable diffusion anisotropy.•Homonuclear decoupling enhances RDC measurement accuracy in proteins.•1H–1H decoupled Cα–Hα RDCs show improved fit to ubiquitin structure. 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–Hα 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 HzN–Hzα terms, thereby facilitating analysis of intraresidue interactions. Application to the NOESY spectrum of a hexapeptide fragment of the intrinsically disordered protein α-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.