Disruption of the H-bond network in the main access channel of catalase-peroxidase modulates enthalpy and entropy of Fe(III) reduction (Articolo in rivista)

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  • Disruption of the H-bond network in the main access channel of catalase-peroxidase modulates enthalpy and entropy of Fe(III) reduction (Articolo in rivista) (literal)
Anno
  • 2010-01-01T00:00:00+01:00 (literal)
Alternative label
  • Vlasits J., Bellei M., Jakopitsch C., De Rienzo F., Furtmuller P.G., Zamocky M., Sola M., Battistuzzi G. and Obinger C. (2010)
    Disruption of the H-bond network in the main access channel of catalase-peroxidase modulates enthalpy and entropy of Fe(III) reduction
    in Journal of inorganic biochemistry
    (literal)
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  • Vlasits J., Bellei M., Jakopitsch C., De Rienzo F., Furtmuller P.G., Zamocky M., Sola M., Battistuzzi G. and Obinger C. (literal)
Pagina inizio
  • 648 (literal)
Pagina fine
  • 656 (literal)
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  • 104 (literal)
Rivista
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  • Acknowledgement: This work was supported by the Ministero dell'Universita e della Ricerca Scientifica (MUR) of Italy (Programmi di Ricerca Scientifica di Rilevante Interesse Nazionale 2007 Prot. N. 2007KAWXCL and n. 20079Y9578), by the University of Modena and Reggio Emilia (Fondo di Ateneo per la Ricerca, 2007), and the Austrian Science Fund FWF projects P18751 and P20996. (literal)
Note
  • ISI Web of Science (WOS) (literal)
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  • 1. Univ Nat Resources & Appl Life Sci, Dept Chem, Div Biochem, BOKU, A-1190 Vienna, Austria (Vlasits J., Jakopitsch C., Furtmuller P.G., Zamocky M., Obinger C.) 2. Univ Modena & Reggio Emilia, Dept Chem, I-41125 Modena, Italy (Bellei M., De Rienzo F., Sola M., Battistuzzi G.) 3. CNR Ist Nanosci, Ctr S3, I-41125 Modena, Italy (De Rienzo F., Sola M.) (literal)
Titolo
  • Disruption of the H-bond network in the main access channel of catalase-peroxidase modulates enthalpy and entropy of Fe(III) reduction (literal)
Abstract
  • Catalase-peroxidases are the only heme peroxidases with substantial hydrogen peroxide dismutation activity. In order to understand the role of the redox chemistry in their bifunctional activity, catalatically-active and inactive mutant proteins have been probed in spectroelectrochemical experiments. In detail, wildtype KatG from Synechocystis has been compared with variants with (i) disrupted KatG-typical adduct (Trp122-Tyr249-Met275), (ii) mutation of the catalytic distal His123-Arg119 pair, and (iii) altered accessibility to the heme cavity (Asp152, Ser335) and modified charge at the substrate channel entrance (Glu253). A valuable insight into the mechanism of reduction potential (E degrees') modulation in KatG has been obtained from the parameterization of the corresponding enthalpic and entropic components, determined from the analysis of the temperature dependence of E degrees'. Moreover, model structures of ferric and ferrous Synechocystis KatG have been computed and used as reference to analyze and discuss the experimental data. The results, discussed by reference to published resonance Raman data on the strength of the proximal iron-imidazole bond and catalytic properties, demonstrate that E degrees' of the Fe(III)/Fe(II) couple is not strongly correlated with the bifunctional activity. Besides the importance of an intact Trp-Tyr-Met adduct, it is the architecture of the long and constricted main channel that distinguishes KatGs from monofunctional peroxidases. An ordered matrix of oriented water dipoles is important for H2O2 oxidation. Its disruption results in modification of enthalpic and entropic contributions to E degrees' that reflect reduction-induced changes in polarity, electrostatics, continuity and accessibility of solvent to the metal center as well as alterations in solvent reorganization. (C) 2010 Elsevier Inc. All rights reserved. (literal)
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