Figure 1
GTase activity of SdgB and SdgA using mass spectrometry. (a, b) Mass spectra of the synthesized DSD (a) and DSDSD (b) peptides. The observed peaks correspond to a sodium adduct [M+Na]+ of the peptides. (c, d) Mass spectra of the DSD (c) and DSDSD (d) peptides incubated with SdgB and UDP-GlcNAc. The expected O-GlcNAcylation of serine is shown as a blue chemical structure to the right of the peak. (e, f) Mass spectra of the peptides incubated with SdgA and UDP-GlcNAc. GlcNAcylation was not detected. (g, h) Mass spectra of the peptides incubated with both SdgB and SdgA in the presence of UDP-GlcNAc. The expected second GlcNAcylations by SdgA, which are shown as red chemical structures to the right of the peak, were not detected in this study. All mass values are listed as the monoisotopic mass. |