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Oxygen Activation and Reduction in Respiration: Involvement of Redox-Active Tyrosine 244

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Science  24 Nov 2000:
Vol. 290, Issue 5496, pp. 1588-1591
DOI: 10.1126/science.290.5496.1588

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Abstract

Cytochrome oxidase activates and reduces O2 to water to sustain respiration and uses the energy released to drive proton translocation and adenosine 5′-triphosphate synthesis. A key intermediate in this process, P, lies at the junction of the O2-reducing and proton-pumping functions. We used radioactive iodide labeling followed by peptide mapping to gain insight into the structure of P. We show that the cross-linked histidine 240–tyrosine 244 (His240-Tyr244) species is redox active in P formation, which establishes its structure as FeIV=O/CuB 2+-H240-Y244·. Thus, energy transfer from O2 to the protein moiety is used as a strategy to avoid toxic intermediates and to control energy utilization in subsequent proton-pumping events.

  • * To whom correspondence should be addressed. E-mail: babcock{at}cem.msu.edu

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