text: 4.  At a substrate concentration of 20 µM, the most active << HFC >> glucuronidation catalysts were UGT1A10 followed by UGT1A6 >UGT1A7 >UGT2A1, whereas at 300 µM [[ UGT1A6 ]] was about 10 times better catalyst than the other recombinant UGTs.