Enhanced Sialylation of Albumin-erythropoietin by Controlling Combination Ratio of Hexose in CHO Cell Cultures

초록

Sialylation of therapeutic proteins reduces clearance rates because sialic acids can prevent the glycoprotein from binding asialoglycoprotein receptors. Many studies have been focused on enhancing sialylation due to its pivotal role in plasma half-life of therapeutic glycoproteins [1]. The amount of available carbon sources in medium causes differences in microheterogeneity of glycans, because nucleotide sugars are synthesized from carbon sources [2]. In this study, we investigated the effects of hexose combination ratios (glucose: galactose: mannose) on sialylation of a fusion protein, albumin-erythropoietin (Alb-EPO). Since nucleotide sugars interact with each other, addition of carbon sources in combination can change the amount of sialylation on produced proteins, compared to those with separate addition. The hexoses were added in nine different conditions depending on the combination of three kinds of hexoses in two concentrations for each. As a result of hexose feeding, it was found that there was a tendency of sialylation on Alb-EPO due to the change in the rate of sugar uptake and interconversion of nucleotide sugar. In conclusion, various concentrations of the mixed sugars can change sialylation patterns, and the total sialic acid contents of Alb-EPO were increased by controlling the concentrations of available carbon sources.