Catalytic reduction of dioxygen with modified Thermus thermophilus cytochrome c552

Jonathan Husband, Michael S. Aaron, Rajneesh K. Bains, Andrew R. Lewis, Jeffrey J. Warren

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4 Citations (SciVal)


Efficient catalysis of the oxygen reduction reaction (ORR) is of central importance to function in fuel cells. Metalloproteins, such as laccase (Cu) or cytochrome c oxidase (Cu/Fe–heme) carry out the 4H+/4e− reduction quite efficiently, but using large, complex protein frameworks. Smaller heme proteins also can carry out ORR, but less efficiently. To gain greater insight into features that promote efficient ORR, we expressed, characterized, and investigated the electrochemical behavior of six new mutants of cytochrome c552 from Thermus thermophilus: V49S/M69A, V49T/M69A, L29D/V49S/M69A, P27A/P28A/L29D/V49S/M69A, and P27A/P28A/L29D/V49T/M69A. Mutation to V49 causes only minor shifts to FeIII/II reduction potentials (E°′), but introduction of Ser provides a hydrogen bond donor that slightly enhances oxygen reduction activity. Mutation of L29 to D induces small shifts in heme optical spectra, but not to E°′ (within experimental error). Replacement of P27 and P28 with A in both positions induces a − 50 mV shift in E°′, again with small changes to the optical spectra. Both the optical spectra and reduction potentials have signatures consistent with peroxidase enzymes. The V49S and V49T mutations have the largest impact of ORR catalysis, suggesting that increased electron density at the Fe site does not improve O2 reduction chemistry.
Original languageEnglish
Pages (from-to)8-14
Number of pages7
JournalJournal of Inorganic Biochemistry
Early online date20 Jan 2016
Publication statusPublished - 1 Apr 2016

Bibliographical note

The Simon Fraser University President's Research Start up Grant and the National Sciences and Engineering Research Council (RGPIN05559 to J. J. W.) supported this work. John Thompson assisted with the collection of Raman spectra and Kara Bren provided helpful advice on 13C NMR acquisition.


  • Electrochemistry
  • Heme proteins
  • Oxygen reduction
  • Proton relay


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