title: Evaluating (13)C enrichment data of free amino acids for precise metabolic flux analysis.
abstract: Metabolic flux analysis using (13)C enrichment data of intracellular free amino acids (FAAs) can improve the time resolution of flux estimation compared to analysis of proteinogenic amino acid data owing to the faster turnover times of FAAs. The nature of the (13)C enrichment dynamics of FAAs remains obscure, however, especially with regard to its dependence on culture conditions, even though an understanding of dynamic behavior is important for precise metabolic flux estimation. In this study, we analyzed the (13)C enrichment dynamics of free and proteinogenic amino acids in a series of continuous culture experiments with Escherichia coli. The results indicated that the effect of protein degradation on the (13)C enrichment of FAAs was negligible under cellular growth conditions. Furthermore, they showed that the time scale necessary for (13)C enrichment dynamics of FAAs to reach a steady state depends on culture conditions such as oxygen uptake rate, which was likely due to different pool sizes of intracellular metabolites. The results demonstrate the importance of analyzing (13)C enrichment dynamics for the precise estimation of metabolic fluxes using FAA data.
authors: Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Osaka, Japan.
authors: Eiji
authors: E
authors: Mori
authors: Chikara
authors: C
authors: Furusawa
authors: Shuichi
authors: S
authors: Kajihata
authors: Tomokazu
authors: T
authors: Shirai
authors: Hiroshi
authors: H
authors: Shimizu
mesh_terms: D000596:Amino Acids / Q000032:analysis* / Q000378:metabolism*; D019149:Bioreactors; D053898:Biosynthetic Pathways; D002247:Carbon Isotopes / Q000032:analysis / Q000378:metabolism; D003470:Culture Media / Q000378:metabolism; D048168:Escherichia coli K12 / Q000254:growth & development / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D005947:Glucose / Q000378:metabolism / Q000493:pharmacokinetics; D007553:Isotope Labeling / Q000379:methods*; D060847:Metabolic Engineering; D008954:Models, Biological; D010100:Oxygen / Q000378:metabolism / Q000493:pharmacokinetics; D059748:Proteolysis
chemical_list: D000596:Amino Acids; D002247:Carbon Isotopes; D003470:Culture Media; D005947:Glucose; D010100:Oxygen