Fig. 2.
Inhibition of the hSULT2A1-catalyzed sulfation of (A) 1.0 µM DHEA and (B) 0.4 µM pregnenolone by major metabolites of tamoxifen. Sulfation rates of uninhibited controls for endoxifen, N-desTAM, 4-OHTAM, and TAM-NO were 87, 98, 97, and 111 nmol/min per mg, respectively, for DHEA sulfation, whereas the uninhibited rates for these metabolites were 63, 92, 68, and 90 nmol/min per mg, respectively, when determining the sulfation of pregnenolone. Data are mean ± S.E. from triplicate determinations.