title: X-ray structure of a vanadium-containing enzyme: chloroperoxidase from the fungus Curvularia inaequalis.
abstract: The chloroperoxidase (EC 1.11.1.-) from the fungus Curvularia inaequalis belongs to a class of vanadium enzymes that oxidize halides in the presence of hydrogen peroxide to the corresponding hypohalous acids. The 2.1 A crystal structure (R = 20%) of an azide chloroperoxidase complex reveals the geometry of the catalytic vanadium center. Azide coordinates directly to the metal center, resulting in a structure with azide, three nonprotein oxygens, and a histidine as ligands. In the native state vanadium will be bound as hydrogen vanadate(V) in a trigonal bipyramidal coordination with the metal coordinated to three oxygens in the equatorial plane, to the OH group at one apical position, and to the epsilon 2 nitrogen of a histidine at the other apical position. The protein fold is mainly alpha-helical with two four-helix bundles as main structural motifs and an overall structure different from other structures. The helices pack together to a compact molecule, which explains the high stability of the protein. An amino acid sequence comparison with vanadium-containing bromoperoxidase from the seaweed Ascophyllum nodosum shows high similarities in the regions of the metal binding site, with all hydrogen vanadate(V) interacting residues conserved except for lysine-353, which is an asparagine.
authors.affiliation: Max Planck Institute of Biochemistry, D-82152 Martinsried, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Messerschmidt
authors.forename: R
authors.initials: R
authors.lastname: Wever
mesh_terms: D000595:Amino Acid Sequence; D002711:Chloride Peroxidase / Q000648:ultrastructure*; D016384:Consensus Sequence; D018360:Crystallography, X-Ray; D005658:Fungi / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008667:Metalloproteins / Q000648:ultrastructure*; D008969:Molecular Sequence Data; D010544:Peroxidases / Q000737:chemistry; D011489:Protein Denaturation; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013696:Temperature; D014639:Vanadium
chemical_list: D008667:Metalloproteins; D014639:Vanadium; D010544:Peroxidases; C026195:bromide peroxidase; D002711:Chloride Peroxidase