title: Kinetics of Spanish broom peroxidase obeys a Ping-Pong Bi-Bi mechanism with competitive inhibition by substrates.
abstract: In plants, adverse conditions often induce an increase in reactive oxygen species (ROS) such as hydrogen peroxide (H2O2). H2O2 is reduced to water, and thus becomes detoxified by enzymes such as Cytisus multiflorus peroxidase (CMP). Here, the steady-state kinetics of the H2O2-supported oxidation of different organic substrates by CMP was investigated. Analysis of the initial rates vs. H2O2 and reducing substrate concentrations proved to be consistent with a substrate-inhibited Ping-Pong Bi-Bi reaction mechanism. The phenomenological approach expresses the peroxidase Ping-Pong mechanism in the form of the Michaelis-Menten equation and affords an interpretation of the effects in terms of the kinetic parameters [Formula: see text] , [Formula: see text] , kcat, [Formula: see text] , [Formula: see text] and of the microscopic rate constants, k1 and k3, of the shared three-step catalytic cycle of peroxidases.
authors.affiliation: Centro de Investigación y Desarrollo Tecnológico del Agua (CIDTA), Universidad de Salamanca, 37007 Salamanca, Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Pérez Galende
authors.affiliation: Instituto de Estudios Biofuncionales, Departamento de Química-Física II, Facultad de Farmacia, Universidad Complutense de Madrid, 28040 Madrid, Spain.
authors.forename: Nazaret
authors.initials: N
authors.lastname: Hidalgo Cuadrado
authors.affiliation: Department of Biochemistry, Microbiology and Biotechnology, Far Eastern Federal University, 690600 Vladivostok, Russia.
authors.forename: Eduard Ya
authors.initials: EY
authors.lastname: Kostetsky
authors.affiliation: Centro de Investigación y Desarrollo Tecnológico del Agua (CIDTA), Universidad de Salamanca, 37007 Salamanca, Spain; Departamento de Química Física, Universidad de Salamanca, 37008 Salamanca, Spain. Electronic address: mgr@usal.es.
authors.forename: Manuel G
authors.initials: MG
authors.lastname: Roig
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Universidad de Salamanca, 37007 Salamanca, Spain.
authors.forename: Enrique
authors.initials: E
authors.lastname: Villar
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Universidad de Salamanca, 37007 Salamanca, Spain.
authors.forename: Valery L
authors.initials: VL
authors.lastname: Shnyrov
authors.affiliation: Chembiotech Laboratories, Kyrewood House, Tenbury Wells, Worcestershire WR15 8SG, UK. Electronic address: jfk@chembiotech.co.uk.
authors.forename: John F
authors.initials: JF
authors.lastname: Kennedy
mesh_terms: D055162:Biocatalysis; D029865:Cytisus / Q000201:enzymology*; D006139:Guaiacol / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D006139:Guaiacol; D006861:Hydrogen Peroxide; D009195:Peroxidase
keywords: Heme peroxidase; Microscopic constants; Ping-Pong Bi–Bi Mechanism