Characterization of a Peroxodiiron(III) Intermediate in the T201S Variant of Toluene/o-Xylene Monooxygenase Hydroxylase from Pseudomonas sp. OX1

• Authors: Woon Ju Song, Massachusetts Institute of Technology; Rachel K. Behan, Massachusetts Institute of Technology; Naik Naik, Emory University; B H Vincent Huynh, Emory University; Stephen J. Lippard, Massachusetts Institute of Technology
• Journal Title: Journal of the American Chemical Society
• Volume: Volume 131, Number 17
• Publisher: American Chemical Society | 2009-05-06, Pages 6074-6075
• Type of Work: Article | Post-print: After Peer Review
• Publisher DOI: http://doi.org/10.1021/ja9011782
• Subjects: Chemistry, General

Abstract

We report the observation of a novel intermediate in the reaction of a reduced toluene/o-xylene monooxygenase hydroxylase (ToMOHred) T201S variant, in the presence of a regulatory protein (ToMOD), with dioxygen. This species is the first oxygenated intermediate with an optical band in any toluene monooxygenase. The UV-Vis and Mössbauer spectroscopic properties of the intermediate allowing us to assign it as a peroxodiiron(III) species, T201Speroxo, similar to Hperoxo in methane monooxygenase. Although T201S generates T201Speroxo in addition to optically transparent ToMOHperoxo, previously observed in wild type ToMOH, this conservative variant is catalytically active in steady state catalysis and single turnover experiments, and displays the same regiospecificity for toluene and slightly different regiospecificity for o-xylene oxidation.