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Redox Intermediates in the Catalase Cycle of Catalase-Peroxidases from Synechocystis PCC 6803, Burkholderia pseudomallei, and Mycobacterium tuberculosis

Jakopitsch, Christa ; Vlasits, Jutta ; Wiseman, Ben ; Loewen, Peter C ; Obinger, Christian

Biochemistry (Easton), 2007-02, Vol.46 (5), p.1183-1193 [Periódico revisado por pares]

United States: American Chemical Society

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  • Título:
    Redox Intermediates in the Catalase Cycle of Catalase-Peroxidases from Synechocystis PCC 6803, Burkholderia pseudomallei, and Mycobacterium tuberculosis
  • Autor: Jakopitsch, Christa ; Vlasits, Jutta ; Wiseman, Ben ; Loewen, Peter C ; Obinger, Christian
  • Assuntos: Bacterial Proteins ; Burkholderia pseudomallei ; Burkholderia pseudomallei - enzymology ; Catalase - metabolism ; Hydrogen Peroxide - metabolism ; Kinetics ; Mycobacterium tuberculosis ; Mycobacterium tuberculosis - enzymology ; Oxidation-Reduction ; Peracetic Acid - metabolism ; Peroxidases - metabolism ; Spectrum Analysis ; Synechocystis ; Synechocystis - enzymology
  • É parte de: Biochemistry (Easton), 2007-02, Vol.46 (5), p.1183-1193
  • Notas: This work was supported by the Austrian Science Funds (FWF Project P18751). This work was also supported by grants from the Natural Sciences and Engineering Research Council of Canada (to P.C.L.) and by the Canadian Research Chair Program (to P.C.L.).
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  • Descrição: Monofunctional catalases (EC 1.11.1.6) and catalase-peroxidases (KatGs, EC 1.11.1.7) have neither sequence nor structural homology, but both catalyze the dismutation of hydrogen peroxide (2H2O2 → 2H2O + O2). In monofunctional catalases, the catalatic mechanism is well-characterized with conventional compound I [oxoiron(IV) porphyrin π-cation radical intermediate] being responsible for hydrogen peroxide oxidation. The reaction pathway in KatGs is not as clearly defined, and a comprehensive rapid kinetic and spectral analysis of the reactions of KatGs from three different sources (Synechocystis PCC 6803, Burkholderia pseudomallei, and Mycobacterium tuberculosis) with peroxoacetic acid and hydrogen peroxide has focused on the pathway. Independent of KatG, but dependent on pH, two low-spin forms dominated in the catalase cycle with absorbance maxima at 415, 545, and 580 nm at low pH and 418 and 520 nm at high pH. By contrast, oxidation of KatGs with peroxoacetic acid resulted in intermediates with different spectral features that also differed among the three KatGs. Following the rate of H2O2 degradation by stopped-flow allowed the linking of reaction intermediate species with substrate availability to confirm which species were actually present during the catalase cycle. Possible reaction intermediates involved in H2O2 dismutation by KatG are discussed.
  • Editor: United States: American Chemical Society
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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