Absorbance spectra of CYP101J2 (A), CYP101J3 (B), and CYP101J4 (C) in 50 mM Tris, pH 7.4, of the different forms: oxidized (full black line), oxidized in the presence of 1,8-cineole (full gray line), reduced by the addition of sodium dithionite in the presence of 1,8-cineole (broken black line), and reduced and in complex with CO in the presence of 1,8-cineole (broken gray line). AU, arbitrary units.