title: How covalent heme to protein bonds influence the formation and reactivity of redox intermediates of a bacterial peroxidase.
abstract: The most striking feature of mammalian peroxidases, including myeloperoxidase and lactoperoxidase (LPO) is the existence of covalent bonds between the prosthetic group and the protein, which has a strong impact on their (electronic) structure and biophysical and chemical properties. Recently, a novel bacterial heme peroxidase with high structural and functional similarities to LPO was described. Being released from Escherichia coli, it contains mainly heme b, which can be autocatalytically modified and covalently bound to the protein by incubation with hydrogen peroxide. In the present study, we investigated the reactivity of these two forms in their ferric, compound I and compound II state in a multi-mixing stopped-flow study. Upon heme modification, the reactions between the ferric proteins with cyanide or H2O2 were accelerated. Moreover, apparent bimolecular rate constants of the reaction of compound I with iodide, thiocyanate, bromide, and tyrosine increased significantly and became similar to LPO. Kinetic data are discussed and compared with known structure-function relationships of the mammalian peroxidases LPO and myeloperoxidase.
authors.affiliation: From the Department of Chemistry, Division of Biochemistry, Vienna Institute of BioTechnology, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Markus
authors.initials: M
authors.lastname: Auer
authors.affiliation: From the Department of Chemistry, Division of Biochemistry, Vienna Institute of BioTechnology, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Andrea
authors.initials: A
authors.lastname: Nicolussi
authors.affiliation: From the Department of Chemistry, Division of Biochemistry, Vienna Institute of BioTechnology, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Georg
authors.initials: G
authors.lastname: Schütz
authors.affiliation: From the Department of Chemistry, Division of Biochemistry, Vienna Institute of BioTechnology, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria paul.furtmueller@boku.ac.at.
authors.forename: Paul G
authors.initials: PG
authors.lastname: Furtmüller
authors.affiliation: From the Department of Chemistry, Division of Biochemistry, Vienna Institute of BioTechnology, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria christian.obinger@boku.ac.at.
authors.forename: Christian
authors.initials: C
authors.lastname: Obinger
mesh_terms: D001965:Bromides / Q000737:chemistry; D002384:Catalysis; D003486:Cyanides / Q000737:chemistry; D004583:Electrons; D004926:Escherichia coli / Q000201:enzymology*; D006418:Heme / Q000737:chemistry*; D006735:Horseradish Peroxidase / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D007454:Iodides / Q000737:chemistry; D007501:Iron / Q000737:chemistry; D007784:Lactoperoxidase / Q000737:chemistry; D008956:Models, Chemical; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D009195:Peroxidase / Q000737:chemistry*; D010544:Peroxidases / Q000737:chemistry*; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D013053:Spectrophotometry; D013861:Thiocyanates / Q000737:chemistry; D014443:Tyrosine / Q000737:chemistry
chemical_list: D001965:Bromides; D003486:Cyanides; D007454:Iodides; D013861:Thiocyanates; D014443:Tyrosine; D006418:Heme; D006861:Hydrogen Peroxide; D007501:Iron; D006735:Horseradish Peroxidase; D007784:Lactoperoxidase; D010544:Peroxidases; D009195:Peroxidase; C031760:thiocyanate; D010100:Oxygen
keywords: Covalently Bound Heme; Halide Oxidation; Heme; Innate Immunity; Kinetics; Lactoperoxidase; Myeloperoxidase; Peroxidase; Posttranslational Modification; Stopped-flow Kinetics