Molecular cloning, structure, and reactivity of the second bromoperoxidase from Ascophyllum nodosum.
Wischang D, Radlow M, Schulz H, Vilter H, Viehweger L, Altmeyer MO, Kegler C, Herrmann J, Müller R, Gaillard F, Delage L, Leblanc C, Hartung J.
Bioorg Chem. 2012 Oct;44:25-34. doi: 10.1016/j.bioorg.2012.05.003. Epub 2012 Jun 23.
Fachbereich Chemie, Organische Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Strasse, D-67663 Kaiserslautern, Germany.
Abstract
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 °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.
Copyright © 2012 Elsevier Inc. All rights reserved.
PMID:
22884431
[PubMed – indexed for MEDLINE]