Fig. 3

Expression of the fluorescent sfGFP-AhR. a SDS-PAGE (acrylamide 12 %) separation of protein samples obtained after the expression of the sfGFP-AhR, showing total cell extract before (lane 1) and after 16 h (lane 2) of IPTG induction, soluble fraction (lane 3) and the lysate of the inclusion bodies in 8 M urea (lane 4). Detection of migrated proteins was done by a coomassie blue staining. b Fluorescence of serial concentrations of the sfGFP and sfGFP-AhR was measured at the wavelength 485 nm for excitation (EX) and 538 nm for emission (EM). The values were expressed as a relative fluorescent unit (RFU) and the accuracy is shown next to each curve (R²). (Inset) Fluorescence spectra of the different proteins (30 μg/ml) and the fluorophore fluorescein (1 μg/ml) were determined by measuring RFU at available pairs of wavelengths on the Fluoroskan Ascent® microplate reader. Blank conditions represent the fluorescence of PBS-containing wells