Transglycosylation of genistein and sophoricoside by PmCGTase and its variants.

The transglycosylation of genistein by CGTases was performed as previously described (29). Briefly, the whole reaction solution (1 ml) contained 200 μl of 0.05 mg/ml purified wild-type or mutant CGTases (diluted with pH 6 PBS buffer), 200 μl of genistein or sophoricoside (2 g/liter) dissolved in dimethyl sulfoxide (DMSO) as the glycosyl acceptor, and 600 μl of maltodextrin (10 g/liter) dissolved in 50 mM of PBS buffer (pH 6) as the glycosyl donor. The whole reaction solution was mixed in a 2-ml closed tube and shaken for the appropriate time on a 120-rpm rotary shaker at 40°C for 12 h. Then the reaction products were determined by HPLC. Similarly, the transglycosylation of sophoricoside was performed by replacing genistein with sophoricoside as the glycosyl acceptor.