Molecular cloning, structure, and reactivity of the second bromoperoxidase from Ascophyllum nodosum

作者：Wischang Diana; Radlow Madlen; Schulz Heiko; Vilter Hans; Viehweger Lutz; Altmeyer Matthias O; Kegler Carsten; Herrmann Jennifer; Mueller Rolf; Gaillard Fanny; Delage Ludovic; Leblanc Catherine; Hartung Jens^*

来源：Bioorganic Chemistry, 2012, 44: 25-34.

DOI：10.1016/j.bioorg.2012.05.003

• Ascophyllum nodosum
• Bromoperoxidase
• Fucales
• Kinetics
• Linear free energy relationship
• Organobromine synthesis
• Oxidation catalysis
• Phenol bromination
• Vanadium

The sequence of bromoperoxidase II from the brown alga Ascophyllum nodosum was determined from a full length cloned cDNA, obtained from a tandem mass spectrometry RT-PCR-approach. The clone encodes a protein composed of 641 amino-acids, which provides a mature 67.4 kDa-bromoperoxidase II-protein (620 amino-acids). Based on 43% sequence homology with the previously characterized bromoperoxidase I from A. nodosum, a tertiary structure was modeled for the bromoperoxidase II. The structural model was refined on the basis of results from gel filtration and vanadate-binding studies, showing that the bromoperoxidase II is a hexameric metalloprotein, which binds 0.5 equivalents of vanadate as cofactor per 67.4 kDa-subunit, for catalyzing oxidation of bromide by hydrogen peroxide in a bi-bi-ping-pong mechanism (k(cat) = 153 s(-1), 22 degrees C, pH 5.9). Bromide thereby is converted into a bromoelectrophile of reactivity similar to molecular bromine, based on competition kinetic data on phenol bromination and correlation analysis. Reactivity provided by the bromoperoxidase II mimics biosynthesis of methyl 4-bromopyrrole-2-carboxylate, a natural product isolated from the marine sponge Axinella tenuidigitata.

• 出版日期2012-10