title: hNCOcanH pulse sequence and a robust protocol for rapid and unambiguous assignment of backbone ((1)H(N), (15)N and (13)C') resonances in (15)N/(13)C-labeled proteins.
abstract: A three-dimensional nuclear magnetic resonance (NMR) pulse sequence named as hNCOcanH has been described to aid rapid sequential assignment of backbone resonances in (15)N/(13)C-labeled proteins. The experiment has been derived by a simple modification of the previously described HN(C)N pulse sequence [Panchal et al., J. Biomol. NMR 20 (2001) 135-147]; t2 evolution is used to frequency label (13)C' rather than (15)N (similar trick has also been used in the design of hNCAnH pulse sequence from hNcaNH [Frueh et al., JACS, 131 (2009) 12880-12881]). The modification results in a spectrum equivalent to HNCO, but in addition to inter-residue correlation peaks (i.e. Hi , Ci-1), the spectrum also contains additional intra-residue correlation peaks (i.e. Hi-1 , Ci-1) in the direct proton dimension which has maximum resolution. This is the main strength of the experiment and thus, even a small difference in amide (1) H chemical shifts (5-6 Hz) can be used for establishing a sequential connectivity. This experiment in combination with the HNN experiment described previously [Panchal et al., J. Biomol. NMR 20 (2001) 135-147] leads to a more robust assignment protocol for backbone resonances ((1) H(N) , (15)N) than could be derived from the combination of HNN and HN(C)N experiments [Bhavesh et al., Biochemistry, 40 (2001) 14727-14735]. Further, this new protocol enables assignment of (13)C' resonances as well. We believe that the experiment and the protocol presented here will be of immense value for structural-and functional-proteomics research by NMR. Performance of this experiment has been demonstrated using (13)C/(15)N labeled ubiquitin.
authors.affiliation: Center of Biomedical Magnetic Resonance, Sanjay Gandhi Post-Graduate Institute of Medical Sciences Campus, Raibareli Road, Lucknow 226014, Uttar Pradesh, India; Department of Chemical Sciences, Tata Institute of Fundamental Research, 1-Homi Bhabha Road, Colaba, Mumbai 400005, India.
authors.forename: Dinesh
authors.initials: D
authors.lastname: Kumar
authors.forename: Ramakrishna V
authors.initials: RV
authors.lastname: Hosur
mesh_terms: D002247:Carbon Isotopes / Q000737:chemistry; D009587:Nitrogen Isotopes / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D017510:Protein Folding; D011522:Protons; D025801:Ubiquitin / Q000737:chemistry*
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D011522:Protons; D025801:Ubiquitin