title: Direct detection of N-H[...]N hydrogen bonds in biomolecules by NMR spectroscopy.
abstract: A nuclear magnetic resonance (NMR) experiment is described for the direct detection of N-H[...]N hydrogen bonds (H-bonds) in 15N isotope-labeled biomolecules. This quantitative HNN-COSY (correlation spectroscopy) experiment detects and quantifies electron-mediated scalar couplings across the H-bond (H-bond scalar couplings), which connect magnetically active (15)N nuclei of the H-bond donor and acceptor. Detectable H-bonds comprise the imino H-bonds in canonical Watson-Crick base pairs, many H-bonds in unusual nucleic acid base pairs and H-bonds between protein backbone or side-chain N-H donor and N acceptor moieties. Unlike other NMR observables, which provide only indirect evidence of the presence of H-bonds, the H-bond scalar couplings identify all partners of the H-bond, the donor, the donor proton and the acceptor in a single experiment. The size of the scalar couplings can be related to H-bond geometries and as a time average to H-bond dynamics. The time required to detect the H-bonds is typically less than 1 d at millimolar concentrations for samples of molecular weight < or = approximately 25 kDa. A C15N/13C-labeled potato spindle tuber viroid T1 RNA domain is used as an example to illustrate this procedure.
authors.affiliation: Department of Chemistry and School of Biological Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Dingley
authors.forename: Lydia
authors.initials: L
authors.lastname: Nisius
authors.forename: Florence
authors.initials: F
authors.lastname: Cordier
authors.forename: Stephan
authors.initials: S
authors.lastname: Grzesiek
mesh_terms: D002247:Carbon Isotopes; D006860:Hydrogen Bonding; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011506:Proteins / Q000737:chemistry*; D012367:RNA, Viral / Q000737:chemistry
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D011506:Proteins; D012367:RNA, Viral