Abstract: In order to understand the effects of ammonia on production and N-glycosylation of antibody fusion protein（AFP）during fed-batch cultures of Chinese hamster ovary（CHO）cells and to reveal the N-glycosylation steps affected by ammonia,the CHO cell maintenance and metabolism,protein production,and N-glycan structure of AFP at different ammonia concentrations were investigated during cell maintenance phase（protein production phase）. It was found that cell growth profile,glucose and glutamine consumption,production level of lactate and ammonia during cell maintenance phase were insignificantly affected at 5-12 mmol/L of ammonia concentration. However,elevated ammonia concentration（>5 mmol/L）led to decreased sialylation and galactosylation but no effect on fucosylation and high mannose species of AFP. The productivity and final titer of AFP decreased while ammonia concentration was > 9 mmol/L. Thus,ammonia production should be carefully controlled < 5 mmol/L during the development of cell culture process to avoid impaired galactosylation and sialylation of the product and decreased product expression from ammonia accumulation.

Key words: CHO cell culture, ammonia, antibody fusion protein, N-glycosylation, sialic acid