Department of Automatic Control, University of Mons, Boulevard Dolez 31, 7000 Mons, Belgium.
J Biotechnol. 2010 Dec;150(4):497-508. doi: 10.1016/j.jbiotec.2010.09.944. Epub 2010 Nov 11.
In this article the metabolic flux analysis of growing CHO-320 cells is performed for a detailed metabolic network which involves 100 reactions and embraces all the significant pathways describing the metabolism of CHO cells. The purpose is to investigate the efficiency of the flux analysis when it is based on a relatively small set of extracellular measurements that can be easily achieved in most laboratories. In this case the flux analysis problem leads to a generally underdetermined mass balance system, as data are not sufficient to uniquely define the metabolic fluxes. Our main contribution is to show that, provided the system of mass balance equations is well-posed, although it is underdetermined, very narrow intervals may be found for most fluxes. The importance of checking the well-posedness of the problem is emphasized and the influence of the number of available measurements on the accuracy of the metabolic flux intervals is systematically investigated. In all cases the computed flux intervals are bounded and a single well defined value is obtained for the formation rates of the cellular macromolecules (proteins, DNA, RNA, lipids) that are not measured. The potential gain of a simple theoretical assumption regarding the metabolism of Threonine is also discussed and compared with an optimal solution calculated by maximizing the biomass formation rate. Alternative network structures obtained by inverting the direction of reversible reactions are also considered. Finally, the results of the metabolic flux analysis are exploited to estimate the total energy production resulting from the metabolism of growing CHO-320 cells.
本文对生长中的 CHO-320 细胞进行代谢通量分析，其代谢网络包含 100 个反应，涵盖了描述 CHO 细胞代谢的所有重要途径。目的是研究当通量分析基于大多数实验室都能轻松获得的相对较小的一组细胞外测量值时的效率。在这种情况下，通量分析问题会导致质量平衡系统普遍欠定，因为数据不足以唯一确定代谢通量。我们的主要贡献是表明，只要质量平衡方程组是适定的，尽管它是欠定的，大多数通量都可以找到非常狭窄的区间。强调了检查问题适定性的重要性，并系统地研究了可用测量值的数量对代谢通量区间准确性的影响。在所有情况下，计算出的通量区间都是有界的，并且对于未测量的细胞大分子（蛋白质、DNA、RNA、脂质）的形成速率，都会得到一个单一明确的值。还讨论了关于苏氨酸代谢的简单理论假设的潜在收益，并将其与通过最大化生物量形成速率计算的最优解进行了比较。还考虑了通过反转可逆反应方向获得的替代网络结构。最后，利用代谢通量分析的结果来估计生长中的 CHO-320 细胞代谢产生的总能量。
