Induction of photochemical auto-reduction of cytochrome-c oxidase by an organic peroxide.
Cytochrome-c oxidase aa3 (CcO) from Paracoccus denitrificans interacts with tertiary butyl hydroperoxide (t-Bu-O-O-H, TBHP) by forming an adduct as indicated by an absorption shift at 408/432 nm and the induction of photochemical autoreduction. The adduct was stable at room temperature for several days even under aerobic conditions. Upon irradiation (413 nm) of the adduct, a photoproduct, similar to the oxygenated mixed valence species (607 nm form), was formed, as indicated by the 418/442 and 607 nm signals in the absorption-difference spectrum. It is concluded that the adduct formation changes the photochemical properties of heme a3. A molecular model for the binding mechanism of TBHP to CcO and for the photochemistry of heme a3-TBHP adduct is proposed.
Leiden Institute of Chemistry, University of Leiden, The Netherlands. j.matysik@chem.leidenuniv.nl
J
J
Matysik
P
P
Hildebrandt
B
B
Ludwig
D003576:Electron Transport Complex IV / Q000737:chemistry*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010777:Photochemistry; D013059:Spectrum Analysis, Raman; D020122:tert-Butylhydroperoxide / Q000737:chemistry*
D020122:tert-Butylhydroperoxide; D003576:Electron Transport Complex IV