Metabolic flux analysis is a useful tool for unraveling relationships between metabolism and cell function. Material balancing can be used to provide estimates of major metabolic pathway fluxes, provided all significant metabolite uptake and production rates are measured. Potential sources of metabolizable material in many serum‐free media formulations are low molecular weight digests of biological material such as yeast extracts and plant or animal tissue hydrolysates. These digests typically contain large amounts of peptides, which may be utilized as amino acids. This article demonstrates the need for accounting for amino acids liberated from peptides in order to accurately estimate pathway fluxes in Chinese hamster ovary cells grown in a complex (hydrolysate containing) medium. A simplified model of central carbon metabolism provides the framework for analyzing external metabolite measurements. Redundant measurements are included to ensure the consistency of data and assumed biochemistry by comparing redundant measurements with their predicted values from a minimum data set, and by expressing the degree of agreement using a statistical “consistency index.” The consistency index tests whether redundancies are satisfied within expected experimental error. For chemostat steady states of CHO cultures grown in a hydrolysate‐supplemented medium, consistent data were obtained only when amino acids liberated from peptides were taken into account. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 62: 324–335, 1999.

Asparagine linked (N‐linked) glycosylation is an important modification of recombinant proteins, because the attached oligosaccharide chains can significantly alter protein properties. Potential glycosylation sites are not always occupied with oligosaccharide, and site occupancy can change with the culture environment. To investigate the relationship between metabolism and glycosylation site occupancy, we studied the glycosylation of recombinant human interferon‐γ (IFN‐γ) produced in continuous culture of Chinese hamster ovary cells. Intracellular nucleotide sugar levels and IFN‐γ glycosylation were measured at different steady states which were characterized by central carbon metabolic fluxes estimated by material balances and extracellular metabolite rate measurements. Although site occupancy varied over a rather narrow range, we found that differences correlated with the intracellular pool of UDP‐N‐acetylglu‐ cosamine + UDP‐N‐acetylgalactosamine (UDP‐GNAc). Measured nucleotide levels and estimates of central carbon metabolic fluxes point to UTP depletion as the cause of decreased UDP‐GNAc during glucose limitation. Glucose limited cells preferentially utilized available carbon for energy production, causing reduced nucleotide biosynthesis. Lower nucleoside triphosphate pools in turn led to lower nucleotide sugar pools and reduced glycosylation site occupancy. Subsequent experiments in batch and fed‐batch culture have confirmed that UDP‐sugar concentrations are correlated with UTP levels in the absence of glutamine limitation. Glutamine limitation appears to influence glycosylation by reducing amino sugar formation and hence UDP‐GNAc concentration. The influence of nucleotide sugars on site occupancy may only be important during periods of extreme starvation, since relatively large changes in nucleotide sugar pools led to only minor changes in glycosylation. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 62: 336–347, 1999.

The year 2020 brought the onslaught of a global crisis in the form of the COVID-19 pandemic. While nearly every facet of everyday life and work was impacted by the pandemic, the biopharmaceutical industry found silver linings in innovation, partnership, and resiliency, all of which contributed to unprecedented speed in developing and delivering vaccines and therapies. The 7 th International Conference on Accelerating Biopharmaceutical Development (AccBio 2021) brought together industry leaders to share experiences from the past year and discuss how lessons learned from the pandemic can be carried forward into the future of biopharmaceutical development. Presenters highlighted examples such as introducing biotherapeutics derived from non-clonal cell pools into the clinic, developing modular or platform technologies, and taking novel risks, among others. These strategies for enabling speed to clinic and launch, as well as for sustaining a robust supply chain, are likely to be integrated into future programs to ensure biomanufacturing resiliency and get medicines to patients faster than pre-pandemic times. 1.This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as

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