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Steady State Redox Levels in Cytochrome Oxidase: Relevance for in Vivo Near Infrared Spectroscopy (Nirs)

  • Chris E. Cooper
  • Martyn A. Sharpe
  • Maria G. Mason
  • Peter Nicholls
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 645)

Abstract

In the visible/NIR (600 – 900 nm) three different redox centres are potentially detectable in vivo in mitochondrial cytochrome c oxidase: haem a (605nm), the binuclear haem a 3/CuB centre (655 nm) and CuA (830 nm). In this paper we report changes in the steady state reduction of these centres following increases in the rate of electron entry into the purified enzyme complex under conditions of saturating oxygen tension. As turnover is increased all three centres becomes progressively reduced. Analysis of the steady states indicated that all three centres remained in apparent equilibrium with cytochrome c throughout the titration. The calculated redox potentials of CuA (+224 mV) and haem a (+267 mV) were consistent with previous equilibrium data. The 655 nm band was also found to be oxygen and flux sensitive. It may be a useful additional in vivo detectable chromophore. However, it titrated with an apparent redox potential of +230mV, far from its equilibrium value (+400 mV). The implications of these results for the interpretation of non invasive measurements of mitochondrial function are discussed.

Keywords

Redox State Cytochrome Oxidase Near Infrared Spectroscopy Redox Centre Redox Titration 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • Chris E. Cooper
    • 1
  • Martyn A. Sharpe
    • 2
  • Maria G. Mason
    • 1
  • Peter Nicholls
    • 1
  1. 1.Department of Biological SciencesUniversity of Essex Wivenhoe ParkColchester EssexUK
  2. 2.Biochemistry and Molecular Biology DepartmentMichigan State UniversityEast LansingUSA

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