TY - JOUR
T1 - Carbon-13 chemical shielding tensors in l-threonine
AU - Janes, Nathan
AU - Ganapathy, Subramanian
AU - Oldfield, Eric
N1 - Funding Information:
* This work was supported in part by the U.S. National Institutes of Health (Grant HLl9481), by the American Heart Association (Grant 80-867), and by the U.S. National Science Foundation (Grants PCM 7!)-23 170,8 I-178 13), and has benetlted from facilities made available by the University of Illinois-National Science Foundation Regional Instrumentation Facility (Grant CHE 79-16 100). t Present addreas: Department of Chemistry, University of Minnesota, 139 Smith Hall, 207 Pleasant St. S. E., Minneapolis, Minn. 55455. I: USPHSR esearch Career Development Awardee, 1979-1984 (Grant CA-00595).
PY - 1983/8
Y1 - 1983/8
N2 - The carbon-13 chemical shielding tensors of the amino acid L-threonine have been determined by solid state proton-enhanced NMR of a single crystal at 3.52 T. For the first time a carbinol shielding tensor is determined quantitatively and unambiguously: the most shielded axis lies 4° from the CO bond. A coordinate system which approximates the alpha carbon tensor orientation is proposed, and it is suggested that this "local symmetry" may be general to many amino acid alpha carbons. The carboxyl and methyl tensor orientations closely approximate previously established "local symmetry," although the methyl (Cγ) C3v symmetry is slightly disrupted, apparently by the neighboring (Oγ) oxygen. The influence of the carbon-nitrogen dipolar interaction on the observed spectra is discussed, and used to make unique assignments for the carboxyl, alpha, and beta carbon tensors.
AB - The carbon-13 chemical shielding tensors of the amino acid L-threonine have been determined by solid state proton-enhanced NMR of a single crystal at 3.52 T. For the first time a carbinol shielding tensor is determined quantitatively and unambiguously: the most shielded axis lies 4° from the CO bond. A coordinate system which approximates the alpha carbon tensor orientation is proposed, and it is suggested that this "local symmetry" may be general to many amino acid alpha carbons. The carboxyl and methyl tensor orientations closely approximate previously established "local symmetry," although the methyl (Cγ) C3v symmetry is slightly disrupted, apparently by the neighboring (Oγ) oxygen. The influence of the carbon-nitrogen dipolar interaction on the observed spectra is discussed, and used to make unique assignments for the carboxyl, alpha, and beta carbon tensors.
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U2 - 10.1016/0022-2364(83)90150-6
DO - 10.1016/0022-2364(83)90150-6
M3 - Article
AN - SCOPUS:0001703498
SN - 0022-2364
VL - 54
SP - 111
EP - 121
JO - Journal of Magnetic Resonance (1969)
JF - Journal of Magnetic Resonance (1969)
IS - 1
ER -