Dioxygen activation at non-heme diiron centers: oxidation of a proximal residue in the I100W variant of toluene/o-xylene monooxygenase hydroxylase.

ABSTRACT: At its carboxylate-bridged diiron active site, the hydroxylase component of toluene/o-xylene monooxygenase activates dioxygen for subsequent arene hydroxylation. In an I100W variant of this enzyme, we characterized the formation and decay of two species formed by addition of dioxygen to the reduced, diiron(II) state by rapid-freeze quench (RFQ) EPR, Mössbauer, and ENDOR spectroscopy. The dependence of the formation and decay rates of this mixed-valent transient on pH and the presence of phenol, propylene, or acetylene was investigated by double-mixing stopped-flow optical spectroscopy. Modification of the alpha-subunit of the hydroxylase after reaction of the reduced protein with dioxygen-saturated buffer was investigated by tryptic digestion coupled mass spectrometry. From these investiga

SUBMITTER: Murray LJ 

PROVIDER: S-EPMC2494530 | biostudies-literature | 2007 Dec

REPOSITORIES: biostudies-literature