Energy metabolism and ATP balance in animal cell cultivation using a stoichiometrically based reaction network

Abstract

A metabolic reaction network is developed for the estimation of the stoichiometric production of adenosine triphosphate (ATP) in animal cell culture. By using the material balance data from fed‐batch and batch cultures of hybridoma cells, the stoichiometric ATP productions are determined with estimated effective P/O ratios of 2 for NADH and 1.2 for FADH2. A significant percentage of the ATP requirement (16–41%) in hybridoma cells is generated directly from free energy release without the participation of oxygen. The oxidative phosphorylation of NADH accounts for about 60% of the total ATP production in the fed‐batch cultures and about 47% in the batch culture. The oxidative phosphorylation of FADH2 accounts for less then 20% of the total ATP production in all cases. A fractional model is devised to analyze the contribution of each nutrient to the ATP production. Results show that a majority of the ATP is produced from glucose metabolism (60–76%). Less than 30% of the ATP is derived from glutamine, and less than 11% is derived from other essential amino acids. The analysis also shows that the glycolytic pathway generates more ATP in the batch (41%) than in the fed‐batch (<27%) cultures. The TCA cycle provides 51–68% of the total ATP production. The calculated stoichiometric oxygen consumption differs among the batch and fed‐batch cultures, depending on the glucose concentration. This result suggests that the relationship between the oxygen uptake rate (OUR) and cell growth may change with the culture conditions. However, the calculated respiratory quotient (RQ) is relatively constant in all cases. A linear relationship is obtained between the specific ATP production rate and the specific cell growth rate. The maximum ATP yield and the maintenance ATP requirement are determined based on this linear relationship. The biosynthetic ATP demand estimated from the dry cell weight and cell composition is significantly lower than that calculated from the maximum ATP yield, indicating that the non‐growth‐associated ATP demand may contain other factors than what is considered in the estimation of the biosynthetic ATP demand. © 1996 John Wiley & Sons, Inc.

A detailed metabolic flux analysis of an underdetermined network of CHO cells

“…However, the general qualitative trend is similar (but with a larger magnitude) to that observed in Xie and Wang (1996b) for Hybridomas. For instance, NAD(P)H is the main source of energy, around 84% of the total ATP production.…”

“…As compared with the results found in the literature (Henry et al, 2005;Xie and Wang, 1996b), the net ATP production through our metabolic network for CHO cells appears to be far more important than the ATP production for Hybridoma cells.…”

“…For instance, NAD(P)H is the main source of energy, around 84% of the total ATP production. It also appears that the TCA cycle provides the major part of the energy, around 76%, a percentage close to that given in Xie and Wang (1996b) where the TCA cycle provides 51-68% of the total ATP production for Hybridoma cells. Similar results were obtained in Henry et al (2005) also for Hybridomas.…”

Apoptosis and Its Suppression in Hepatocytes Culture

“…The question of the mechanisms at play in the regulation of apoptosis by amino acids has been an area of study that has ignited much research interest. Pathways proposed have implicated failure of nucleotide and protein synthesis, expression of 'new' pro-apoptotic genes, reduction of intracellular ATP pools due redox imbalance and collapse of mitochondrial membrane (Rabinovitz 1992;Mecille and Massie 1994;Galle et al 1995;Xie and Wang 1996;Simpson et al 1998). Clearly, amino acid deprivation can elicit an apoptotic response using several mechanisms.…”

Modelling sponge-symbiont metabolism

“…This energetic cost is unknown for both A. queenslandica and AqS1. A reported NGAM cost for a hybridoma cell line was 28.6 mmol ATP per 10^9 cells per hour (Xie & Wang, 2003). With an average dry weight of 450 pg per cell (Lake-Ee Quek, personal communication), an NGAM value of 6.36 mmol ATP / h / gDW was assumed for A. queenslandica.…”