title: Implications for the catalytic mechanism of the vanadium-containing enzyme chloroperoxidase from the fungus Curvularia inaequalis by X-ray structures of the native and peroxide form.
abstract: Implications for the catalytic mechanism of the vanadium-containing chloroperoxidase from the fungus Curvularia inaequalis have been obtained from the crystal structures of the native and peroxide forms of the enzyme. The X-ray structures have been solved by difference Fourier techniques using the atomic model of the azide chloroperoxidase complex. The 2.03 A crystal structure (R = 19.7%) of the native enzyme reveals the geometry of the intact catalytic vanadium center. The vanadium is coordinated by four non-protein oxygen atoms and one nitrogen (NE2) atom from histidine 496 in a trigonal bipyramidal fashion. Three oxygens are in the equatorial plane and the fourth oxygen and the nitrogen are at the apexes of the bipyramid. In the 2.24 A crystal structure (R = 17.7%) of the peroxide derivate the peroxide is bound to the vanadium in an eta2-fashion after the release of the apical oxygen ligand. The vanadium is coordinated also by 4 non-protein oxygen atoms and one nitrogen (NE2) from histidine 496. The coordination geometry around the vanadium is that of a distorted tetragonal pyramid with the two peroxide oxygens, one oxygen and the nitrogen in the basal plane and one oxygen in the apical position. A mechanism for the catalytic cycle has been proposed based on these X-ray structures and kinetic data.
authors.affiliation: Max-Planck-Institut für Biochemie, Martinsried bei München, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Messerschmidt
authors.forename: L
authors.initials: L
authors.lastname: Prade
authors.forename: R
authors.initials: R
authors.lastname: Wever
mesh_terms: D001665:Binding Sites; D002384:Catalysis; D002711:Chloride Peroxidase / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D005583:Fourier Analysis; D006860:Hydrogen Bonding; D003904:Mitosporic Fungi / Q000201:enzymology*; D008958:Models, Molecular; D010545:Peroxides / Q000737:chemistry; D011487:Protein Conformation; D017968:Vanadium Compounds / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D010545:Peroxides; D017968:Vanadium Compounds; D002711:Chloride Peroxidase