Effect of ManNAc and its Derivatives on Glycosylation to Proteins Produced by Mammalian Cell Culture

Various biologics are produced by mammalian cell culture, and for their activities, glycosylation is a pivotal modification. Proteins synthesized in prokaryotes cells such as E. coli were not glycosylated. So proteins should be produced in eucaryotes, such as yeasts and insect cells. In particular, mammalian cells were extensively used because they add proper glycochains to proteins in comparison with other eucaryotes cells. Among the sugar chains, sialic acid, the terminal sugar in N-linked complex glycan structures, is important for the stability of glycoprotein in vivo and so it is required to increase the content of sialic acids in glycoproteins. N - Acetyl - D - mannosamine ( ManNAc), intracellular precursor for sialic acid synthesis, can be incorporated into cells from culture media. Gu et al. reported that supplement of ManNAc to the culture successfully elevated glycosylation level (Biotech. and Bioeng., 58, p. 642, 1998). In this study, we aimed at application of AcManNAc, derivative of ManNAc. AcManNAc was added into BHK cell culture in order to increase sialic acid content of glycoprotein. The effect of AcManNAc on sialylation was superior to that of ManNAc. This result implies that not ManNAc but AcManNAc is a suitable precursor to produce glycoproteins sialylated at high level in the BHK cell culture.