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Updated: Aug 12, 2026

Metabolic Pathway Confirmation and Discovery Through 13C-labeling of Proteinogenic Amino Acids
Published on: January 26, 2012
13N isotope studies of glutamine assimilation pathways in Neurospora crassa
J Calderón1, A J Cooper, A S Gelbard
1Departamento de Ecologia Molecular, Universidad Nacional Autónoma de México, Morelos.
Abstract:
L-[amide-13N]glutamine in Neurospora crassa is metabolized to [13N]glutamate by glutamate synthase and to [13N]ammonium by the glutamine transaminase-omega-amidase pathway. The [13N]ammonium released is assimilated by glutamate dehydrogenase and glutamine synthetase, confirming the operation of a glutamine cycle. Most of the nitrogen is retained during cycling between glutamate and glutamine.
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