title: The ferric-hydroperoxo complex of chloroperoxidase.
abstract: The hydroperoxo-ferric complex, or Compound 0 (Cpd 0), is an unstable transient intermediate common for oxygen activating heme enzymes such as the cytochromes P450, nitric oxide synthases, and heme oxygenases, as well as the peroxidases and catalases which utilize hydrogen peroxide as a source of oxygen and reducing equivalents. Detailed understanding of the mechanism of oxygen activation and formation of the higher valent catalytically active intermediates in heme enzyme catalysis requires the structural and spectroscopic characterization of this immediate precursor, Cpd 0. Using the method of cryoradiolytic reduction of the oxy-ferrous heme complex, we have prepared and characterized hydroperoxo-ferric complex in chloroperoxidase (CPO) and compared this to the same intermediate generated in cytochrome P450 CYP101. Optical absorption spectrum of Cpd 0 in CPO has a Soret band at 449 nm and poorly resolved alpha, beta bands at 576 and 546 nm.
authors.affiliation: Department of Biochemistry, 116 Morrill Hall, University of Illinois, 505 South Goodwin Avenue, Urbana, IL 61801, USA.
authors.forename: Ilia G
authors.initials: IG
authors.lastname: Denisov
authors.forename: John H
authors.initials: JH
authors.lastname: Dawson
authors.forename: Lowell P
authors.initials: LP
authors.lastname: Hager
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Sligar
mesh_terms: D002711:Chloride Peroxidase / Q000737:chemistry* / Q000378:metabolism*; D007501:Iron / Q000737:chemistry* / Q000378:metabolism*; D010545:Peroxides / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D013053:Spectrophotometry
chemical_list: D010545:Peroxides; D007501:Iron; D002711:Chloride Peroxidase