title: Structure and quantum chemical characterization of chloroperoxidase compound 0, a common reaction intermediate of diverse heme enzymes.
abstract: We have determined the crystal structure of the chloroperoxidase (CPO) hydroperoxo reaction intermediate (CPO compound 0) at 1.75-A resolution. The intermediate was generated through controlled photoreduction of the CPO oxygen complex during x-ray data collection, which was monitored by recording of the crystal absorption spectra. Initially, the peroxo-anion species was formed and then protonated to yield compound 0. Quantum chemical calculations indicate that the peroxo-anion species is not stable and collapses instantaneously to compound 0. Compound 0 is present in the ferric low-spin doublet ground state and is characterized by a long O O bond length of 1.5 A and a Fe O bond distance of 1.8 A, which is also observed in the crystal structure.
authors.affiliation: Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Kühnel
authors.forename: Etienne
authors.initials: E
authors.lastname: Derat
authors.forename: James
authors.initials: J
authors.lastname: Terner
authors.forename: Sason
authors.initials: S
authors.lastname: Shaik
authors.forename: Ilme
authors.initials: I
authors.lastname: Schlichting
mesh_terms: D001665:Binding Sites; D002711:Chloride Peroxidase / Q000378:metabolism*; D003460:Crystallization; D005290:Ferric Compounds / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry*
chemical_list: D005290:Ferric Compounds; D006861:Hydrogen Peroxide; D002711:Chloride Peroxidase