title: Structural investigation of the cofactor-free chloroperoxidases.
abstract: The structures of cofactor-free haloperoxidases from Streptomyces aureofaciens, Streptomyces lividans, and Pseudomonas fluorescens have been determined at resolutions between 1.9 A and 1.5 A. The structures of two enzymes complexed with benzoate or propionate identify the binding site for the organic acids which are required for the haloperoxidase activity. Based on these complexes and on the structure of an inactive variant, a reaction mechanism is proposed for the halogenation reaction with peroxoacid and hypohalous acid as reaction intermediates. Comparison of the structures suggests that a specific halide binding site is absent in the enzymes but that hydrophobic organic compounds may fit into the active site pocket for halogenation at preferential sites.
authors.affiliation: Department SF, GBF (Gesellschaft für Biotechnologische Forschung), Mascheroder Weg 1, Braunschweig, D-38124, FRG.
authors.forename: B
authors.initials: B
authors.lastname: Hofmann
authors.forename: S
authors.initials: S
authors.lastname: Tölzer
authors.forename: I
authors.initials: I
authors.lastname: Pelletier
authors.forename: J
authors.initials: J
authors.lastname: Altenbuchner
authors.forename: K H
authors.initials: KH
authors.lastname: van Pée
authors.forename: H J
authors.initials: HJ
authors.lastname: Hecht
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002711:Chloride Peroxidase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011549:Pseudomonas / Q000201:enzymology*; D016415:Sequence Alignment; D017421:Sequence Analysis; D013302:Streptomyces / Q000201:enzymology*; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; D002711:Chloride Peroxidase