Skip to Main content Skip to Navigation
Journal articles

Mechanism of Chloride Inhibition of Bilirubin Oxidases and Its Dependence on Potential and pH

Abstract : Bilirubin oxidases (BODs) belong to the multicopper oxidase (MCO) family and efficiently reduce O2 at neutral pH and under physiological conditions where chloride concentrations are >100 mM. BODs were consequently considered to be Cl− resistant, as opposed to laccases. However, there has not been a detailed study of the related effect of chloride and pH on the redox state of immobilized BODs. Here, we investigate by electrochemistry the catalytic mechanism of O2 reduction by the thermostable Bacillus pumilus BOD immobilized on carbon nanofibers in the presence of NaCl. The addition of chloride results in the formation of a redox state of the enzyme, previously observed for different BODs and laccases, which is active only after a reductive step. This behavior has not been previously investigated. We show that the kinetics of formation of this state is strongly dependent on pH, temperature, Cl− concentration, and applied redox potential. Ultraviolet−visible spectroscopy allows us to correlate the inhibition by chloride with the formation of the alternative resting form of the enzyme. We demonstrate that O2 is not required for its formation and show that the application of an oxidative potential is sufficient. In addition, our results suggest that reactivation may proceed through T3β.
Document type :
Journal articles
Complete list of metadatas

https://hal.archives-ouvertes.fr/hal-01519938
Contributor : Nadine Laffargue <>
Submitted on : Tuesday, May 9, 2017 - 3:44:52 PM
Last modification on : Tuesday, February 4, 2020 - 10:38:08 AM

Links full text

Identifiers

Collections

Citation

Anne De Poulpiquet, Christian H. Kjaergaard, Jad Rouhana, Ievgen Mazurenko, Pascale Infossi, et al.. Mechanism of Chloride Inhibition of Bilirubin Oxidases and Its Dependence on Potential and pH. ACS Catalysis, American Chemical Society, 2017, 7, pp. 3916-3923. ⟨10.1021/acscatal.7b01286⟩. ⟨hal-01519938⟩

Share

Metrics

Record views

195