Journal: bioRxiv
Article Title: Selective Hydrolytic Defluorination of Branched Perfluorooctanoic Acid Isomers by a Haloacid Dehalogenase
doi: 10.64898/2026.04.19.719434
Figure Lengend Snippet: (a) Docking model showing PFOA bound within the active-site pocket of 4A. (b) Enlarged view of the PFOA-binding site, illustrating predicted hydrogen-bonding interactions between the PFOA carboxylate group and surrounding active-site residues. (c) Two-dimensional interaction map of the PFOA–4A complex, highlighting hydrogen-bonding interactions involving the carboxylate group (green dashed lines) and hydrophobic or polar contacts between PFOA and active-site residues. (d) Biosensor-based plate assay detecting fluoride release following high-concentration, scaled-up reactions. PFOA (0.5 mM) was incubated with purified 4A (500 µM) at 20℃ for 120 h prior to analysis. Following incubation, aliquots from the reaction mixture were analyzed using a fluoride-responsive riboswitch biosensor with 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside (X-gal) as the chromogenic substrate. Enzyme-only, substrate-only, buffer-only controls, and fluoride standards (10 and 500 μM KF) are shown.
Article Snippet: 5-Bromo-4-chloro-3-indolyl-β-D-galactopyranoside (X-gal) solution (20 mg/mL; Thermo Fisher Scientific, RO941) and 10 mM Tris buffer (pH 8.0, prepared from a 1 M stock; Thermo Fisher Scientific, AM9855G) were used for enzyme assays.
Techniques: Binding Assay, Concentration Assay, Incubation, Purification