Figure 5. Expanded analysis of the effects of glycosylation on esterase activity.

(A) Tunicamycin treated LS174T cells that were also treated with ManNAc analogues did not experience an increase in esterase activity. (B) Structures of Bu₄GlcNAc and Bu₄GalNAc analogues, which (C) elicited a small or no increase in esterase activity (respectively) in LS174T cells (Bu₄ManNAc was included in this experiment as a positive control). (D) The periodate resorcinol assay was used to measure sialic acid content in 1,3,4-O-Bu₃GlcNAc-treated cells, with 1,3,4-O-Bu₃ManNAc again used as the positive control (no increase in sialic acid levels was observed for GalNAc analogue treated cells, data not shown). (E) Intracellular esterase activity in cells treated with increasing concentrations of unmodified ManNAc. * - indicates a P value of < 0.05 in a two-tailed t test.