Peroxide stimulated transition between the ferryl intermediates of bovine cytochrome c oxidase

• Published in: Biochimica et biophysica acta. Bioenergetics 2021-08, Vol.1862 (8), p.148447-148447, Article 148447
• Main Authors: Sztachova, T., Pechova, I., Mikulova, L., Stupak, M., Jancura, D., Fabian, M.
• Format: Article
• Language: English
• Subjects: Cytochrome c oxidase; Ferryl intermediates; Hydrogen peroxide; Redox state
• ISSN: 0005-2728; 1879-2650
• DOI: 10.1016/j.bbabio.2021.148447

During catalysis of cytochrome c oxidases (CcO) several ferryl intermediates of the catalytic heme a3-CuB center are observed. In the PM ferryl state, produced by the reaction of two-electron reduced CcO with O2, the ferryl iron of heme a3 and a free radical are present at the catalytic center. The radical reduction stimulates the transition of the PM into another ferryl F state. Similar ferryl states can be also generated from the oxidized CcO (O) in the reaction with H2O2. The PM, the product of the reaction of the O with one molecule of peroxide, is transformed into the F state by the second molecule of H2O2. However, the chemical nature of this transition has not been unambiguously elucidated yet. Here, we examined the redox state of the peroxide-produced PM and F states by the one-electron reduction. The F form and interestingly also the major fraction of the PM sample, likely another P-type ferryl form (PR), were found to be the one oxidizing equivalent above the O state. However, the both P-type forms are transformed into the F state by additional molecule of H2O2. It is suggested that the PR-to-F transition is due to the binding of H2O2 to CuB triggering a structural change together with the uptake of H+ at the catalytic center. In the PM-to-F conversion, these two events are complemented with the annihilation of radical by the intrinsic oxidation of the enzyme. •Two ferryl intermediates of cytochrome c oxidase prepared by peroxide•The redox state of the catalytic center of the ferryl intermediates•The peroxide stimulated the transition between the ferryl intermediates•The catalytic activity of ferryl intermediate