Figure 4.

PelX is a Class 3 UDP-GlcNAc C4-epimerase. A and B, ¹H NMR focused on the anomeric H-1 region of the spectra (red line) for (A) UDP-GlcNAc incubated without enzyme (top), UDP-GlcNAc with PelX (middle), and UDP-GalNAc with PelX (bottom) and (B) UDP-Glc incubated without enzyme (top), UDP-Glc with PelX (middle), and UDP-Gal with PelX (bottom). C, PelX catalyzes the epimerization of UDP-GlcNAc to UDP-GalNAc by inversion of the hydroxyl group at position C4. D, LC-MS/MS quantification of GlcNAc from cell extracts of the indicated strains. Error bars represent the S.E. of the mean of six independent biological replicates. Statistical significance was evaluated using unpaired t test. *, p < 0.05.