Characterization of a peroxodiiron(III) intermediate in the T201S variant of toluene/o-xylene monooxygenase hydroxylase from Pseudomonas sp. OX1.
We report the observation of a novel intermediate in the reaction of a reduced toluene/o-xylene monooxygenase hydroxylase (ToMOH(red)) 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 Mossbauer spectroscopic properties of the intermediate allow us to assign it as a peroxodiiron(III) species, T201S(peroxo), similar to H(peroxo) in methane monooxygenase. Although T201S generates T201S(peroxo) in addition to optically transparent ToMOH(peroxo), 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.
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Woon Ju
WJ
Song
Rachel K
RK
Behan
Sunil G
SG
Naik
Boi Hanh
BH
Huynh
Stephen J
SJ
Lippard
D004852:Epoxy Compounds / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D014644:Genetic Variation / Q000235:genetics*; D009154:Mutation; D010105:Oxygenases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011549:Pseudomonas / Q000201:enzymology*
D004852:Epoxy Compounds; D005290:Ferric Compounds; D010105:Oxygenases; C114360:toluene 2-xylene monooxygenase