Table - link
||Bacteria Escherichia coli
||Yuan J, Fowler WU, Kimball E, Lu W, Rabinowitz JD. Kinetic flux profiling of nitrogen assimilation in Escherichia coli. Nat Chem Biol. 2006 Oct2(10):529-30. p. 530 table 1PubMed ID16936719
||"[Researchers] introduce kinetic flux profiling (KFP), a variant of metabolic flux profiling that involves monitoring the dynamics of incorporation of isotope-labeled nutrient into downstream products using LC-MS/MS. The essential concept of KFP is that intracellular metabolites become labeled when cells are switched from unlabeled to isotope labeled nutrient, and metabolites closer to the added nutrient in the metabolic network always get labeled before their downstream products."
||"Glutamate is present in enteric bacteria in amounts ~25-fold larger than those of glutamine (Table 1) (ref 12). Glutamate can be synthesized either directly from ammonia via the glutamate dehydrogenase system or indirectly via glutamine and glutamate synthetase (Fig. 1c). [Researchers] found that glutamate becomes labeled less rapidly than glutamine (kE << kQ, where kE is the rate constant for turnover of glutamate's nitrogen), but the glutamate flux is nevertheless slightly greater than that of glutamine owing to the much larger glutamate pool size (Table 1). Production of double-labeled glutamine precisely mirrored labeling of glutamate, which provides glutamine's amino nitrogen (Fig. 1d). This observation is consistent with the notion that glutamate serves as the parent of doubly labeled glutamine, with kQ >> kE."