title: Solid-state 17O NMR study of the electric-field-gradient and chemical shielding tensors in polycrystalline amino acids.
abstract: We have presented a systematic experimental investigation of carboxyl oxygen electric-field-gradient (EFG) and chemical shielding (CS) tensors in crystalline amino acids. Three 17O-enriched amino acids were prepared: L-aspartic acid, L-threonine, and L-tyrosine. Analysis of two-dimensional 17O multiple-quantum magic-angle spinning (MQMAS), MAS, and stationary NMR spectra yields the 17O CS, EFG tensors and the relative orientations between the two tensors for the amino acids. The values of quadrupolar coupling constants (CQ) are found to be in the range of 6.70-7.60 MHz. The values of deltaiso lie in the range of 268-292 ppm, while those of the delta11 and delta22 components vary from 428 to 502 ppm, and from 303 to 338 ppm, respectively. There is a significant correlation between the magnitudes of delta22 components and C--O bond lengths. Since C--O bond length may be related to hydrogen-bonding environments, solid-state 17O NMR has significant potential to provide insights into important aspects of hydrogen bonds in biological systems.
authors.affiliation: RIKEN Genomic Sciences Center, 1-7-22 Suehiro, Tsurumi, Yokohama, 230-0045 Japan. kyamada@gsc.riken.jp
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Yamada
authors.forename: Tadashi
authors.initials: T
authors.lastname: Shimizu
authors.forename: Masataka
authors.initials: M
authors.lastname: Tansho
authors.forename: Takahiro
authors.initials: T
authors.lastname: Nemoto
authors.forename: Miwako
authors.initials: M
authors.lastname: Asanuma
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Yoshida
authors.forename: Toshio
authors.initials: T
authors.lastname: Yamazaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hirota
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D003460:Crystallization; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008280:Magnetics; D009757:Nylons / Q000737:chemistry*; D010103:Oxygen Isotopes
chemical_list: D000596:Amino Acids; D009757:Nylons; D010103:Oxygen Isotopes