Figure 3

GLT8D1 activity with UDP-Gal as donor. (A) The assay was done as described in M&M using 0.5 mM nucleotide sugar donor, 20 mM monosaccharide, 0.8 µg GLT8D1, for 22 h. Ctr, without enzyme. Assay was done in triplicate and standard deviation is shown. (B) Peak at m/z 384.15 corresponding to the composition HexHexNAc is shown. (C) MS² spectrum of compound at m/z 384.15 (see Fig. S3 for fragment identification). (D) Extracted ion chromatograms (XICs) of m/z 384.1500, which corresponds to the [M + H]⁺ ion of the C₁₄H₂₅NO₁₁ compound. A 5 ppm mass tolerance was used.