title: Four-bond deuterium isotope effects on the chemical shifts of amide nitrogens in proteins.
abstract: An approach towards precision NMR measurements of four-bond deuterium isotope effects on the chemical shifts of backbone amide nitrogen nuclei in proteins is described. Three types of four-bond (15) N deuterium isotope effects are distinguished depending on the site of proton-to-deuterium substitution: (4)ΔN(N(i-1)D), (4)ΔN(N(i+1)D) and (4)ΔN(Cβ,(i-1)D). All the three types of isotope shifts are quantified in the (partially) deuterated protein ubiquitin. The (4)ΔN(N(i+1)D) and (4)ΔN(C(β,i-1)D) effects are by far the largest in magnitude and vary between 16 and 75 ppb and -18 and 46 ppb, respectively. A semi-quantitative correlation between experimental (4)ΔN(N(i+1)D) and (4)ΔN(C(β,i-1)D) values and the distances between nitrogen nuclei and the sites of (1)H-to-D substitution is noted. The largest isotope shifts in both cases correspond to the shortest inter-nuclear distances.
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, 20742, USA.
authors.forename: Vitali
authors.initials: V
authors.lastname: Tugarinov
mesh_terms: D000577:Amides / Q000737:chemistry*; D003903:Deuterium / Q000737:chemistry*; D041961:Deuterium Exchange Measurement; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D009584:Nitrogen / Q000737:chemistry*; D011522:Protons; D025801:Ubiquitin / Q000737:chemistry*
chemical_list: D000577:Amides; D011522:Protons; D025801:Ubiquitin; D003903:Deuterium; D009584:Nitrogen
keywords: chemical shifts; deuteration; deuterium isotope shifts; isotope filtering