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Gewählte Publikation:

Vlasits, J; Jakopitsch, C; Schwanninger, M; Holubar, P; Obinger, C; .
(2007): Hydrogen peroxide oxidation by catalase-peroxidase follows a non-scrambling mechanism.
FEBS Lett. 2007; 581(2):320-324 FullText FullText_BOKU

Despite catalyzing the same reaction (2H(2)O(2) -> 2H(2)O + O-2) heme-containing monofunctional catalases and bifunctional catalase-peroxidases (KatGs) do not share sequence or structural similarities raising the question of whether or not the reaction pathways are similar or different. The production of dioxygen from hydrogen peroxide by monofunctional catalases has been shown to be a two-step process involving the redox intermediate compound I which oxidizes H2O2 directly to O-2. In order to investigate the origin Of O-2 released in KatG mediated H2O2 degradation we performed a gas chromatography-mass spectrometry investigation of the evolved O-2 from a 50:50 mixture of (H2O2)-O-18/H-2 O-16(2) solution containing KatGs from Mycobacterium tuberculosis and Synechocystis PCC 6803. The GC-MS analysis clearly demonstrated the formation of O-18(2) (mle = 36) and O-16(2) (mle = 32) but not (OO)-O-16-O-18 (ml e = 34) in the pH range 5.6-8.5 implying that O-2 is formed by two-electron oxidation without breaking the O-O bond. Also active site variants of Synechocystis KatG with very low catalase but normal or even enhanced peroxidase activity (D152S, H123E, W122F, Y249F and R439A) are shown to oxidize H2O2 by a non-scrambling mechanism. The results are discussed with respect to the catalatic mechanism of KatG. (c) 2006 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
Autor*innen der BOKU Wien:
Holubar Peter
Jakopitsch Christa
Obinger Christian
Schwanninger Manfred
Find related publications in this database (using NML MeSH Indexing)
Bacterial Proteins/chemistry*;Catalysis;Gas Chromatography-Mass Spectrometry;Hydrogen Peroxide/chemistry*;Hydrogen-Ion Concentration;Mycobacterium tuberculosis/enzymology*;Oxidation-Reduction;Oxygen/chemistry;Peroxidases/chemistry*;Synechocystis/enzymology*;

Find related publications in this database (Keywords)
hydrogen peroxide dismutation
dioxygen release
gas chromatography-mass spectrometry analysis

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