Copper (Cu) is an important trace metal that is essential for a variety of important biological functions. In mammalian cells, enzymes or proteins coordinate with Cu through the side chains of histidine, cysteine, and methionine where Cu is transitioned between different redox states. This unique attribute allows Cu-binding proteins to catalyze key cellular reactions such as electron transfer, energy production, free radical scavenging, and chemical oxidation. Hence, medium Cu concentration impacts cell culture performance and product quality attributes in recombinant monoclonal antibodies (mAbs) produced by Chinese Hamster Ovary (CHO) cells. However, the underlying causes for these metabolic and phenotypic changes are not fully-understood. In this study, we developed, optimized and applied <i>in vitro</i> enzymatic assays to mechanistically understand the impact of Cu on lactate production and on Fc glycan galactosylation in CHO cell culture. Cu deficiency resulted in increased lactate production and was associated with significant reduction in intracellular cytochrome C oxidase (COX) activity for tested cell lines. Low COX activity may lead to impaired mitochondrial respiration and TCA cycle to increase lactate production. Additionally, Cu also impacted Fc glycan galactosylation and an <i>in vitro</i> galactosyltransferase (GalT) assay was used to determine the impact of different trace metals (including Cu) and their concentrations on GalT activity. Our results indicated that Cu impacts GalT activity which impacts galactosylation levels in mAbs produced by CHO cells.

Evaluating the impact of copper on CHO cell metabolism and antibody Fc glycan galactosylation using enzymatic assays

249th National Meeting (2015)

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