THE 2FE2S CENTERS OF THE 2-OXO-1,2-DIHYDROQUINOLINE 8-MONOOXYGENASE FROM PSEUDOMONAS-PUTIDA-86 STUDIED BY EPR SPECTROSCOPY

The 2-oxo-1,2-dihydroquinoline 8-monooxygenase from Pseudomonas putida 86 comprises two components with four redox active sites necessary fo r activity. We present an EPR characterization of the iron-sulfur cent res in the purified reductase and oxygenase component of this novel en zyme system. The oxygenase component was identified as a Rieske [2Fe2S ] protein on the basis of its characteristic EPR spectrum with g(z,y,x ) = 2.01, 1.91, 1.76 and g(av) = 1.893. The reductase component, an ir on-sulfur flavoprotein, contained a [2Fe2S] cluster with g(z,y,x) = 2. 03, 1.94, 1.89 and the average g-value(g(av)) of 1.953, typical of a f erredoxin-type centre. In redox titrations at pH 7, the midpoint poten tials were determined to be -180 mV +/- 30 mV and -100 mV +/- 10 mV fo r the reductase and oxygenase component, respectively. A detailed comp arison to other multicomponent enzyme systems is presented pointing ou t the EPR and redox properties of the FeS centres involved.