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Unambiguous assignment of the H3 S and H3 R deuterations of cerebral (2‐ 13 C) glutamate by 13 C NMR at 18.8 tesla
Author(s) -
Rodrigues Tiago B.,
Violante Inês R.,
Cerdán Sebastián
Publication year - 2010
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.22277
Subject(s) - chemistry , deuterium , glutamate receptor , diastereomer , stereochemistry , isocitrate dehydrogenase , enzyme , biochemistry , physics , receptor , quantum mechanics
We used high‐field 13 C NMR (18.8 T) to assign unambiguously the isotopic shifts induced by the deuterium substitutions of the H3 proR and H3 proS hydrogens of (2‐ 13 C) glutamate in extracts of the brain from deuterated animals. Monodeuterated H3 R or H3 S glutamate diastereoisomers were produced stereospecifically either by chemical synthesis or by coupling the reactions of isocitrate dehydrogenase and aspartate aminotransferase in deuterated medium, respectively. We show that the (3 S ‐ 2 H) or (3 R ‐ 2 H) deuterations induce characteristic small (Δ 2 = −0.058 parts per million (ppm)) or large (Δ 2 = −0.071 ppm) vicinal isotopic shifts upfield of the perprotonated (2‐ 13 C) glutamate resonance (at 55.5 ppm). Isotopically shifted (2‐ 13 C, 3 S ‐ 2 H) or (2‐ 13 C, 3 R ‐ 2 H) glutamate singlets are conveniently observed by high‐field 13 C NMR in brain extracts from deuterated rats. Since the (3 S ‐ 2 H) or (3 R ‐ 2 H) glutamate diastereoisomers are produced stereospecifically by the cytosolic or mitochondrial isoforms of aconitase and isocitrate dehydrogenase, our results will facilitate the 13 C NMR investigation of these enzymatic activities and their role in subcellular glutamate trafficking. Magn Reson Med 63:1088–1091, 2010. © 2010 Wiley‐Liss, Inc.