title: (Model) studies on vanadate-dependent bromo/iodoperoxidase from Ascophyllum nodosum. VO2+ is not incorporated into the active site.
abstract: Vanadate-dependent peroxidase A.n.I, the main isoenzyme (M(r) = 100 kDa) from the seaweed, Ascophyllum nodosum, contains 2 V per enzyme molecule (as shown by ICP-MS metal analysis) after complete reconstitution with vanadate (V), possibly distributed in a 1:1 ratio between the surface and active site. VO2+ is only weakly associated to the surface of A.n.I. There is no transport channel for VO2+. The EPR spectrum of the reduced holoenzyme is anisotropic (axial) already at room temperature, with EPR parameters similar to those of VO2+ complexes of small model peptides such as Ala-His, Gly-Tyr, Gly-Ser, Gly-Glu, Ser-Gly and Phe-Glu. The complex formation between Ala-His and H2VO4- in water has also been investigated (by 51V NMR); the formation constant at pH 7.2 amounts to 266(28) M-1.
authors.affiliation: Faculty of Inorganic Chemistry, University of Bielefeld, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Knüttel
authors.forename: A
authors.initials: A
authors.lastname: Müller
authors.forename: D
authors.initials: D
authors.lastname: Rehder
authors.forename: H
authors.initials: H
authors.lastname: Vilter
authors.forename: V
authors.initials: V
authors.lastname: Wittneben
mesh_terms: D001665:Binding Sites; D004578:Electron Spin Resonance Spectroscopy; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D015394:Molecular Structure; D010544:Peroxidases / Q000737:chemistry / Q000378:metabolism*; D000459:Phaeophyceae / Q000201:enzymology*; D014638:Vanadates / Q000378:metabolism*
chemical_list: D014638:Vanadates; D010544:Peroxidases; C026195:bromide peroxidase