Binding spectra of vorozole to human CYP1B1 expressed in yeast. Microsomal protein (1 mg/ml) was suspended in 0.1 M KPO4 buffer, pH 7.4, and placed in two cuvettes. The difference spectrum was obtained by adding vorozole to a final concentration of 5.0, 20.0, and 80.0 μM dissolved in dimethyl sulfoxide in the sample cuvette, and an equal volume of carrier solvent was added to the reference cuvette.