SULT1B1 stimulates AA-I reactivity with DNA in the presence of NQO1. AA-I or 3-nitrobenzanthrone (100 μM) were incubated with DNA, PAPS, NADPH, 500nM of SULT1 enzymes and/or NQO1. Twenty micrograms of DNA was used for the adduct analysis. (A) Fragment of a 30% polyacrylamide gel following 32P-labeling. dG-AL-II or dA-AL-II (upper and lower band, respectively). Lanes 1–5, 2, 3, 4, 5, 6h incubations of AA-I, NQO1 and DNA, respectively; Lanes 6–10, AA-I, NQO1 and SULT1B1. (B) Time dependence for AL-I-DNA adducts formation. (C) The same experiment using 3-nitrobenzanthrone. Filled circles DNA adducts in the presence of NQO1, open circles represent DNA adducts in the presence of SULT1A2 and NQO1, filled triangles represent DNA adducts in the presence of SULT1B1 and NQO1. Results shown as mean values for at least two independent experiments.