Article ID Journal Published Year Pages File Type
1925847 Archives of Biochemistry and Biophysics 2011 11 Pages PDF
Abstract

The mechanism of the dehalogenation step catalyzed by dehaloperoxidase (DHP) from Amphitrite ornata, an unusual heme-containing protein with a globin fold and peroxidase activity, has remarkable similarity with that of the classical heme peroxidase, horseradish peroxidase (HRP). Based on quantum mechanical/molecular mechanical (QM/MM) modeling and experimentally determined chlorine kinetic isotope effects, we have concluded that two sequential one electron oxidations of the halogenated phenol substrate leads to a cationic intermediate that strongly resembles a Meisenheimer intermediate – a commonly formed reactive complex during nucleophilic aromatic substitution reactions especially in the case of arenes carrying electron withdrawing groups.

Research highlights► HRP and DHP catalyze dehalogenation reaction at an external site. ► Dehalogenation act catalyzed by HRP and DHP proceeds via cationic intermediate. ► Dehalogenation step is not rate limiting.

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