TABLE 2 Glucuronidation activities of UGT1A9Sol.
The protein concentrations in the assays were either 0.18 mg/ml (UGT1A9 ± Triton X-100) or 0.8 mg/ml (UGT1A9Sol), and the detergent concentration, when present, was 0.2% (w/v). The concentration of the different aglycones was 0.5 mM, and that of the UDP-GA was 5 mM. Note that the amounts of protein and UGT in the two 1A9XHC samples were identical. The UGT1A9Sol was assayed using a concentrated cell extract; hence, the protein composition of this fraction is completely different from the membrane sample. Estimations of the relative amount of UGT per protein by immunodetection suggested that the concentration of enzyme per protein in the cell extract was about 100 times lower than in the membranes.