Influence of Cultivation Conditions on Glycosylation Pattern-a Fed-Batch and Continuous Culture Study

Abstract

This project focused on the relationship between cultivation conditions and glycosylation pattern of a recombinant fusion protein produced by a CHO derived cell line. During the investigation it was found that the glycosylation pattern changed during fed-batch cultivation: sialic acid content and antennary complexity increased with cultivation time although ammonium concentration and most likely glycosidase activities --- two factors which reportedly can decrease sialic acid concentration-increased simultaneously. Continuous cultures were performed to identify which environmental and kinetic variables impact the glycosylation process. A change in glycosylation pattern was only found when the specific productivity during a continuous culture was increased transiently by an increase in ferric citrate concentration. This indicated that it is a kinetic variable which influences the glycosylation of the studied fusion protein. Further experiments focused on the glycosylation of intracellular fusion protein and support the hypothesis that specific productivity, or rather the residence time of the protein in the Golgi apparatus, is crucial to the extent of glycosylation. Notably, concentration, molecular weight, and sialic acid content of the fusion protein increased with cultivation time, suggesting that a prolonged residence time in the Golgi apparatus leads to more complete glycosylation.