Dioxygen Activation at Non-Heme Diiron Centers: Characterization of Intermediates in a Mutant Form of Toluene/o-Xylene Monooxygenase Hydroxylase
- 23 May 2006
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 128 (23) , 7458-7459
- https://doi.org/10.1021/ja062762l
Abstract
We report the generation and characterization of an intermediate in a mutant form of the toluene/o-xylene monooxygenase hydroxylase component from Pseudomonas stutzeri OX1. The reaction of chemically reduced I100W variant in the presence of the coupling protein, ToMOD, with dioxygen was monitored by stopped-flow UV/visible spectroscopy. Rapid-freeze quench (RFQ) samples were also generated for EPR and Mössbauer spectroscopy. A transient species is observed in the UV/visible spectrum with an absorption maximum at 500 nm. EPR and Mössbauer spectra of RFQ samples identified this species as a diiron(III,IV) cluster spin-coupled to a neutral W radical. A diamagnetic precursor to the mixed-valent diiron(III,IV) was also observed at an earlier time point, with Mössbauer parameters typical of high-spin FeIII. We have tentatively assigned this antiferromagnetically coupled diiron(III) intermediate as a peroxo-bridged cluster, and this complex has also been observed in preliminary studies of the wild-type hydroxylase.Keywords
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