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Título

The turnover of the H3 deuterons from (2-13C) glutamate and (2-13C) glutamine reveals subcellular trafficking in the brain of partially deuterated rats

AutorCerdán, Sebastián ; Sierra, Alejandra ; Fonseca, Luis L.; Ballesteros, Paloma ; Rodrigues, Tiago B.
Palabras clave13C NMR
Aconitase
Deuterated rats
Isocitrate dehydrogenase
Fecha de publicación2009
EditorJohn Wiley & Sons
CitaciónJournal of Neurochemistry 109(s1): 63-72 (2009)
ResumenWe investigated by 13C NMR the turnover of the H3 deuterons of (2-13C) glutamate and (2-13C) glutamine in the brain of partially deuterated rats. Adult animals (150–200 g) fed ad libitum received 50%2H2O or tap water 9 days before infusing (1-13C) glucose or (2-13C) acetate for 5, 10, 15, 30, 60, or 90 min. The brains were then funnel-frozen and acid extracts were prepared and analyzed by high-resolution 13C NMR. The deuteration of one or the two H3 hydrogens of (2-13C) glutamate or glutamine resulted in single (−0.07 ppm) or double (−0.14 ppm) isotopic shifts upfield of the corresponding C2 perprotonated resonance, demonstrating two sequential deuteration steps. The faster monodeuteration generated 3R or 3S (2-13C, 3-2H) glutamate or glutamine through the alternate activities of cerebral aconitase or isocitrate dehydrogenase, respectively. The slower process produced bideuterated (2-13C, 3,3′-2H2) glutamate or glutamine through the consecutive activity of both enzymes. The kinetics of deuteration was fitted to a Michaelis–Menten model including the apparent Km′ and Vmax′ values for the observed deuterations. Our results revealed different kinetic constants for the alternate and consecutive deuterations, suggesting that these processes were caused by the different cytosolic or mitochondrial isoforms of aconitase and isocitrate dehydrogenase, respectively. The deuterations of (2-13C) glutamate or glutamine followed also different kinetics from (1-13C) glucose or (2-13C) acetate, revealing distinct deuteration environments in the neuronal or glial compartments.
DescripciónTrabajo presentado al Third ISN Special Neurochemistry Conference/8th International Meeting for Brain Energy Metabolism: “Neurodegeneration and Regeneration”.
Versión del editorhttp://dx.doi.org/10.1111/j.1471-4159.2009.05962.x
URIhttp://hdl.handle.net/10261/112024
DOI10.1111/j.1471-4159.2009.05962.x
ISSN0022-3042
E-ISSN1471-4159
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