TcCGT1, which is initiated by the spontaneous deprotonation of the substrate. The spacious binding pocket explains the substrate promiscuity, and the binding pose of the substrate determines C‐ or O‐glycosylation activity. Site‐directed mutagenesis at two residues (I94E and G284K) switched C‐ to O‐glycosylation. TcCGT1 is the first plant CGT with a crystal structure and the first flavone 8‐C‐glycosyltransferase
promiscuity of the new phenolic O‐glycosyltransferase was explored by using phenols from Traditional Chinese Medicinal herbs as substrates. MhGT1 exhibited robust capabilities for the regio‐ and stereospecific O‐glycosylation of 72 structurally diverse drug‐like scaffolds and sterols with uridine diphosphate (UDP) glucose as a sugar donor. Unprecedentedly, MhGT1 showed higher regiospecificities and activities