title: Catalase-like activity of bovine met-hemoglobin: interaction with the pseudo-catalytic peroxidation of anthracene traces in aqueous medium.
abstract: Hemoglobin is a member of the hemoprotein superfamily whose main role is to transport O(2) in vertebrate organisms. It has two known promiscuous enzymatic activities, peroxidase and oxygenase. Here we show for the first time that bovine hemoglobin also presents a catalase-like activity characterized by a V(max )of 344 microM/min, a K(M )of 24 mM and a k(cat) equal to 115/min. For high anthracene and hemoglobin concentrations and low hydrogen peroxide concentrations, this activity inhibits the expected oxidation of anthracene, which occurs through a peroxidase-like mechanism. Anthracene belongs to the polycyclic aromatic hydrocarbon (PAH) family whose members are carcinogenic and persistent pollutants found in industrial waste waters. Our results show that anthracene oxidation by hemoglobin and hydrogen peroxide follows a typical bi-bi ping-pong mechanism with a V(max) equal to 0.250 microM/min, K(M(H2O2) )of 80 microM, K(M(ANT)) of 1.1 microM and k(cat) of 0.17/min. The oxidation of anthracene is shown to be pseudo-catalytic because an excess of hemoglobin and hydrogen peroxide is required to make PAH completely disappear. Thus, bovine hemoglobin presents, in different degrees, all the catalytic activities of the hemoprotein group, which makes it a very interesting protein for biotechnological processes and one with which structure-activity relationships can be studied.
authors.affiliation: Institut Charles Gerhardt Montpellier, Equipe des Matériaux Avancés pour la Catalyse et la Santé, UMR 5253 CNRS/ENSCM/UM2/UM1, 34296 Montpellier, France.
authors.forename: Laveille
authors.initials: L
authors.lastname: Paco
authors.forename: Anne
authors.initials: A
authors.lastname: Galarneau
authors.forename: Jullien
authors.initials: J
authors.lastname: Drone
authors.forename: François
authors.initials: F
authors.lastname: Fajula
authors.forename: Carole
authors.initials: C
authors.lastname: Bailly
authors.forename: Sylviane
authors.initials: S
authors.lastname: Pulvin
authors.forename: Daniel
authors.initials: D
authors.lastname: Thomas
mesh_terms: D000818:Animals; D000873:Anthracenes / Q000737:chemistry / Q000378:metabolism; D001709:Biotechnology; D002374:Catalase / Q000378:metabolism*; D002417:Cattle; D006861:Hydrogen Peroxide / Q000378:metabolism; D008706:Methemoglobin / Q000378:metabolism*; D008954:Models, Biological; D010084:Oxidation-Reduction; D011084:Polycyclic Aromatic Hydrocarbons / Q000378:metabolism
chemical_list: D000873:Anthracenes; D011084:Polycyclic Aromatic Hydrocarbons; D008706:Methemoglobin; D006861:Hydrogen Peroxide; D002374:Catalase; C034020:anthracene