FIGURE 6.

High level detection of biosynthetically modified sialic acids in glycoconjugates of N-acyl-modified ManN-treated virus producer cells. A and B, characterization and quantification of glycolipid-bound sialic acids by DMB-HPLC. 293T cells were treated for 7 days with the respective ManN derivatives. A medium change was performed on day 5. To calculate the concentrations of the occurring sialic acid species, retention peak areas of interest were compared with the retention peak areas of standards (Fig. 5C and data not shown) and normalized to the cytosolic protein concentrations of the respective cell lysates. Internal standards were used for Neu5Ac, Neu5Gc, and Neu5But (Fig. 5B). Concentrations of Neu5Prop and Neu5Cyclo were estimated according to the Neu5Ac standard (*). B, data shown represent the mean values and S.D. of two independent experiments (n = 2).