title: Purification and characterisation of vanadium haloperoxidases from the brown alga Pelvetia canaliculata.
abstract: Two enzymes characterised as iodoperoxidases (PcI and PcII), with vanadium-dependent activity, have been purified from the brown alga Pelvetia canaliculata (L.) Decne et Thur. (Fucaceae, Phaeophyceae), collected in the Northern Portuguese coast, at Viana do Castelo. The relative molecular masses were 166 kDa for PcI and 416 kDa for PcII, as determined by gel filtration. SDS-PAGE shows that PcI has just one band corresponding to a subunit of 66 kDa, while PcII shows four bands (66, 72, 157 and 280 kDa). The following kinetic parameters have been determined from a steady-state analysis of the oxidation of iodide by H2O2: PcI, pHopt = 6.0, KM(I-) = 2.1 mM, KM(H2O2) = 110 microM, Ki(I-) = 127 mM; and PcII, pHopt = 6.5, KM(I-) = 2.4 mM, KM(H2O2) = 20 microM and Ki(I-) = 69 mM. These iodoperoxidases are thermostable, as also observed for vanadium bromo- and chloroperoxidases.
authors.affiliation: Centro de Química Estrutural, Instituto Superior Técnico, Lisboa, Portugal.
authors.forename: M G
authors.initials: MG
authors.lastname: Almeida
authors.forename: M
authors.initials: M
authors.lastname: Humanes
authors.forename: R
authors.initials: R
authors.lastname: Melo
authors.forename: J A
authors.initials: JA
authors.lastname: Silva
authors.forename: J J
authors.initials: JJ
authors.lastname: da Silva
authors.forename: R
authors.initials: R
authors.lastname: Wever
mesh_terms: D020134:Catalytic Domain; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D007453:Iodide Peroxidase / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D008970:Molecular Weight; D000459:Phaeophyceae / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D011174:Portugal; D014639:Vanadium / Q000737:chemistry* / Q000378:metabolism
chemical_list: D014639:Vanadium; C414928:vanadium iodoperoxidase; D007453:Iodide Peroxidase