title: Vanadium haloperoxidases from brown algae of the Laminariaceae family.
abstract: Vanadium haloperoxidases were extracted, purified and characterized from three different species of Laminariaceae--Laminaria saccharina (Linné) Lamouroux, Laminaria hyperborea (Gunner) Foslie and Laminaria ochroleuca de la Pylaie. Two different forms of the vanadium haloperoxidases were purified from L. saccharina and L. hyperborea and one form from L. ochroleuca species. Reconstitution experiments in the presence of several metal ions showed that only vanadium(V) completely restored the enzymes activity. The stability of some enzymes in mixtures of buffer solution and several organic solvents such as acetone, ethanol, methanol and 1-propanol was noteworthy; for instance, after 30 days at least 40% of the initial activity for some isoforms remained in mixtures of 3:1 buffer solution/organic solvent. The enzymes were also moderately thermostable, keeping full activity up to 40 degrees C. Some preliminary steady-state kinetic studies were performed and apparent Michaelis-Menten kinetic parameters were determined for the substrates iodide and hydrogen peroxide. Histochemical studies were also performed in fresh tissue sections from stipe and blade of L. hyperborea and L. saccharina, showing that haloperoxidase activity was concentrated in the external cortex near the cuticle, although some activity was also observed in the inner cortical region.
authors.affiliation: Centro de Electroquímica e Cinética, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, Edifício C1-5 degrees piso, Campo Grande, 1749-016 Lisbon, Portugal.
authors.forename: M
authors.initials: M
authors.lastname: Almeida
authors.forename: S
authors.initials: S
authors.lastname: Filipe
authors.forename: M
authors.initials: M
authors.lastname: Humanes
authors.forename: M F
authors.initials: MF
authors.lastname: Maia
authors.forename: R
authors.initials: R
authors.lastname: Melo
authors.forename: N
authors.initials: N
authors.lastname: Severino
authors.forename: J A
authors.initials: JA
authors.lastname: da Silva
authors.forename: J J
authors.initials: JJ
authors.lastname: Fraústo da Silva
authors.forename: R
authors.initials: R
authors.lastname: Wever
mesh_terms: D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D007453:Iodide Peroxidase / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008970:Molecular Weight; D010544:Peroxidases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D000459:Phaeophyceae / Q000201:enzymology*; D012997:Solvents
chemical_list: D012997:Solvents; D010544:Peroxidases; C026195:bromide peroxidase; C414928:vanadium iodoperoxidase; D007453:Iodide Peroxidase