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How to increase the stability of L-glutamine for better cell performance

L-Glutamine is an important amino acid to improve cell performance and growth

Glutamine is used by practically all human and animal cells as a carbon source for growth and as a building block for proteins. Due to its important role in energy supply, it is typically present in cell culture media at higher concentrations than other amino acids. While free L-glutamine is an important energy source, its use in cell culture media can result in several problems. In particular, it is widely known that the chemical degradation of glutamine into ammonia and pyroglutamate while in liquid media can negatively affect cell culture performance. High uptake and metabolic turnover also result in the release of ammonia which becomes inhibiting to the cell culture.

Glutamine dipeptides are an attractive solution to fix the performance challenges of L-glutamine

One elegant, natural method to stabilize glutamine against chemical degradation through the synthesis of a dipeptide was developed in the field of parenteral nutrition solutions and coworkers more than three decades ago[1]. This approach has since been widely adopted in cell culture media applications, with L-alanyl-L-glutamine being probably the best-known dipeptide that is also available in various ready- to-use supplements. Depending on the cell line, clone, product and media formulation used for biopharmaceutical production, it can be helpful to evaluate additional glutamine dipeptides to maximize performance and keep cells healthier for longer.

L-alanyl-L-glutamine and glycyl-L-glutamine are two dipeptides with superior cell performance

L-alanyl-L-glutamine is one example of a chemically stable dipeptide that can be taken up and metabolized by CHO cells with a similar rate as glutamine. This can result in the typical glycolytic overflow metabolism and the formation of inhibitory concentrations of ammonia and lactic acid. While several approaches have been described to reduce this byproduct formation, the use of alternative L-glutamine dipeptides can represent a simpler solution. Sánchez‑Kopper et al[2] investigated the uptake and metabolism of various dipeptides by CHO cells, and demonstrated that glycyl-L-glutamine is taken up at a lower rate than L-alanyl-L-glutamine. This resulted in slightly reduced growth rate, but higher antibody titer. Although ammonia and lactate concentrations were not reported, it can be assumed the reduced growth rate corresponded to lower rates of formation for these byproducts and potentially higher antibody productivity.

Select Evonik as your supply partner for highly pure, chemically defined glutamine dipeptides

Evonik produces high purity glutamine dipeptides by chemical synthesis and subsequent purification for the cell culture industry at large volume scale. cQrex® GQ (glycl-L-glutamine) and cQrex® AQ (L-alanyl-L-glutamine) are today trusted for use with the biopharmaceutical production processes of many companies worldwide. cQrex® AAQ (acetyl-L-alanyl-L-glutamine) has been further modified to modulate the rate of uptake and metabolism and can be used as an additional tool to fine-tune the supply of glutamine sources. Finally, a ready-to-use supplement called cQrex® AAQplus that consists of a mix of two glutamine dipeptides for optimized antibody productivity has recently been launched.

References

[1] Fuerst, P., The Journal of Nutrition. J Nutr. 2001 Sep; 131(9 Suppl.):2562S-8S.

[2] Sanchez-Kopper et al., AMB Expr 2016; 6:48