(A) SDS-PAGE of ValG and ValG mutant. M, protein marker; I, cell-free extract of E. coli harboring valG; II, purified ValG; III, cell-free extract of E. coli harboring mutated valG; IV, purified ValG mutant. (B) TLC analysis (nPrOH:AcOH:H2O 4:1:1) of ValG reactions. a, validoxylamine A; b, glycosylation product of validoxylamine A with UDP-galactose; c, glycosylation product of validoxylamine A with UDP-glucose.