Heterologous Expression of valG and Characterization of the Glycosyltransferase. (A) SDS-PAGE analysis of ValG protein: 1. molecular weight marker, 2. soluble protein of extract of E. coli BL21Gold(DE3)pLysS/valG before induction, 3. total protein of extract of E. coli BL21Gold(DE3)pLysS/valG after induction with IPTG, 4. soluble protein of line 3, 5. purified his-tagged ValG. (B) TLC analysis of ValG reaction (silica gel, solvent system: nPrOH:AcOH:H2O = 4:1:1); R: validoxylamine A standard, U: ValG reaction using UDP-glucose as glucosyl donor, G: ValG reaction using GDP-glucose as glucosyl donor, A: ValG reaction using ADP-glucose as glucosyl donor, T: ValG reaction using TDP-glucose as glucosyl donor. (C) Conversion scheme of validoxylamine A to VAL-A catalyzed by ValG.