Activity of glutamate dehydrogenase is increased in ammonia-stressed hybridoma cells

• Published in: Biotechnology and bioengineering 1998-02, Vol.57 (4), p.447-453
• Main Authors: Bonarius, Hendrik P. J., Houtman, José H. M., de Gooijer, Cornelis D., Tramper, Johannes, Schmid, Georg
• Format: Article
• Language: English
• Subjects: Amino Acids - metabolism; Ammonia; Animal cell culture; Animal cells; Animals; Bioconversion; Biological and medical sciences; Biosynthesis; Biotechnology; Carbon - metabolism; Catalysis; Catalyst activity; cell culture; Cell Division; Cell hybridization, cell fusion, hybridomas; Cell Survival; Cells, Cultured; Composition effects; Eukaryotic cell cultures; Fundamental and applied biological sciences. Psychology; glutamate dehydrogenase; Glutamate Dehydrogenase - drug effects; Glutamate Dehydrogenase - metabolism; Hybridomas - drug effects; Hybridomas - enzymology; Mammals; mass balance; metabolic flux; Metabolism; Methods. Procedures. Technologies; Nitrogen - metabolism; Quaternary Ammonium Compounds - metabolism; Quaternary Ammonium Compounds - pharmacology; Sectie Proceskunde; Sub-department of Food and Bioprocess Engineering
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/(SICI)1097-0290(19980220)57:4<447::AID-BIT8>3.0.CO;2-M

The effect of added ammonia on the intracellular fluxes in hybridoma cells was investigated by metabolic‐flux balancing techniques. It was found that, in ammonia‐stressed hybridoma cells, the glutamate‐dehydrogenase flux is in the reverse direction compared to control cells. This demonstrates that hybridoma cells are able to prevent the accumulation of ammonia by converting ammonia and α‐ketoglutarate into glutamate. The additional glutamate that is produced by this flux, as compared to the control culture, is converted by the reactions catalyzed by alanine aminotransferase (45% of the extra glutamate) and aspartate aminotransferase (37%), and a small amount is used for the biosynthesis of proline (6%). The remaining 12% of the extra glutamate is secreted into the culture medium. The data suggest that glutamate dehydrogenase is a potential target for metabolic engineering to prevent ammonia accumulation in high‐cell‐density culture. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 447‐453, 1998.