Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Osaka, Japan.
Biotechnol J. 2011 Nov;6(11):1377-87. doi: 10.1002/biot.201000446.
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.
使用细胞内游离氨基酸（FAA）的（13）C 富集数据进行代谢通量分析，可以比分析蛋白质氨基酸数据更快地估计通量，因为 FAA 的周转率更快。然而，FAA 的（13）C 富集动态的性质仍然不清楚，特别是关于其对培养条件的依赖性，尽管了解动态行为对于精确的代谢通量估计很重要。在这项研究中，我们分析了一系列大肠杆菌连续培养实验中游离和蛋白质氨基酸的（13）C 富集动态。结果表明，在细胞生长条件下，蛋白质降解对 FAA 的（13）C 富集的影响可以忽略不计。此外，它们表明，FAA 的（13）C 富集动态达到稳定状态所需的时间尺度取决于培养条件，如摄氧率，这可能是由于细胞内代谢物的池大小不同。研究结果表明，分析（13）C 富集动态对于使用 FAA 数据精确估计代谢通量非常重要。
