An investigation of the iron-sulphur proteins of benzene dioxygenase from Pseudomonas putida by electron-spin-resonance spectroscopy

• Published in: Biochemical journal 1984-02, Vol.217 (3), p.667-673
• Main Authors: Geary, P J, Saboowalla, F, Patil, D, Cammack, R
• Format: Article
• Language: English
• Subjects: Electron Spin Resonance Spectroscopy; Enzyme Activation - drug effects; Ferredoxins; Iron - pharmacology; Iron-Sulfur Proteins - analysis; Metalloproteins - analysis; Mixed Function Oxygenases - metabolism; NAD - pharmacology; Oxidation-Reduction; Pseudomonas - enzymology; Ultracentrifugation
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj2170667

Benzene dioxygenase from Pseudomonas putida comprises three components, namely a flavoprotein (NADH:ferredoxin oxidoreductase; Mr 81000), an intermediate electron-transfer protein, or ferredoxin (Mr 12000) with a [2Fe-2S] cluster, and a terminal dioxygenase containing two [2Fe-2S] iron-sulphur clusters (Mr 215000), which requires two additional Fe2+ atoms/molecule for oxygenase activity. The ferredoxin and the dioxygenase give e.s.r. signals in the reduced state with rhombic symmetry and average g values of 1.92 and 1.896 respectively. The mid-point redox potentials were determined by e.s.r. titration at pH 7.0 to be -155 mV and -112 mV respectively. The signal from the dioxygenase shows pronounced g anisotropy and most closely resembles those of 4-methoxybenzoate mono-oxygenase from Pseudomonas putida and the [2Fe-2S] 'Rieske' proteins of the quinone-cytochrome c region of electron-transport chains of respiration and photosynthesis.