title: Conformation analysis of d-glucaric acid in deuterium oxide by NMR based on its JHH and JCH coupling constants.
abstract: d-Glucaric acid (GA) is an aldaric acid and consists of an asymmetric acyclic sugar backbone with a carboxyl group positioned at either end of its structure (i.e., the C1 and C6 positions). The purpose of this study was to conduct a conformation analysis of flexible GA as a solution in deuterium oxide by NMR spectroscopy, based on J-resolved conformation analysis using proton-proton ((3) JHH ) and proton-carbon ((2) JCH and (3) JCH ) coupling constants, as well as nuclear overhauser effect spectroscopy (NOESY). The (2) JCH and (3) JCH coupling constants were measured using the J-resolved heteronuclear multiple bond correlation (HMBC) NMR technique. NOESY correlation experiments indicated that H2 and H5 were in close proximity, despite the fact that these protons were separated by too large distance in the fully extended form of the chain structure to provide a NOESY correlation. The validities of the three possible conformers along the three different bonds (i.e., C2C3, C3C4, and C4C5) were evaluated sequentially based on the J-coupling values and the NOESY correlations. The results of these analyses suggested that there were three dominant conformers of GA, including conformer 1, which was H2H3:gauche, H3H4:anti, and H4H5:gauche; conformer 2, which was H2H3:gauche, H3H4:anti, and H4H5:anti; and conformer 3, which was H2H3:gauche, H3H4: gauche, and H4H5:anti. These results also suggested that all three of these conformers exist in equilibrium with each other. Lastly, the results of the current study suggested that the conformational structures of GA in solution were 'bent' rather than being fully extended. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Science of Polymeric Materials, Department of Biomaterial Sciences, Graduate School of Agricultural Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Enomoto-Rogers
authors.affiliation: Ensuiko Sugar Refining Co., Ltd, 1-1-1, Fukuura, Kanazawa-ku, Yokohama, Kanagawa, 236-0004, Japan.
authors.forename: Hisaharu
authors.initials: H
authors.lastname: Masaki
authors.affiliation: Ensuiko Sugar Refining Co., Ltd, 1-1-1, Fukuura, Kanazawa-ku, Yokohama, Kanagawa, 236-0004, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ito
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Furihata
authors.affiliation: Science of Polymeric Materials, Department of Biomaterial Sciences, Graduate School of Agricultural Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Tadahisa
authors.initials: T
authors.lastname: Iwata
mesh_terms: D017666:Deuterium Oxide / Q000737:chemistry*; D005937:Glucaric Acid / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D013816:Thermodynamics
chemical_list: D017666:Deuterium Oxide; D005937:Glucaric Acid
keywords: NMR (J-resolved HMBC and NOESY); carbon-proton coupling constant; conformational analysis; glucaric acid