期刊
BIOORGANIC CHEMISTRY
卷 44, 期 -, 页码 25-34出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.bioorg.2012.05.003
关键词
Ascophyllum nodosum; Bromoperoxidase; Fucales; Kinetics; Linear free energy relationship; Organobromine synthesis; Oxidation catalysis; Phenol bromination; Vanadium
资金
- Deutsche Bundesstiftung Umwelt [20008/982]
- Stiftung fur Innovation des Landes Rheinland-Pfalz [818]
- NanoKat
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. (C) 2012 Elsevier Inc. All rights reserved.
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