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Cellular and Molecular Life Sciences CMLS

, Volume 57, Issue 10, pp 1482–1487 | Cite as

The ratio between the fast and slow forms of bovine cytochrome c oxidase is changed by cholate or nucleotides bound to the cholate-binding site close to the cytochrome a3/CuB binuclear centre

  • K. Shoji
  • A. Giuffrè
  • E. D’Itri
  • K. Hagiwara
  • T. Yamanaka
  • M. Brunori*
  • P. Sarti

Abstract.

We determined the fraction of ‘slow’ and ‘fast’ conformations of bovine cytochrome c oxidase, following the kinetics of cyanide binding to the oxidized enzyme. We investigated whether treatment of heart mitochondrial particles with different commercially available types of cholate (standard and ultra-pure) can affect the fraction of cytochrome c oxidase in the two states. Compared to standard cholate, the use of ultra-pure cholate for solubilization of heart mitochondrial particles significantly increased the fraction of the fast enzyme. Complete homogeneity (∼100% fast) was observed when cytochrome c oxidase was solubilized with ultra-pure cholate from heart mitochondrial particles pre-equilibrated with AMP; equilibration with ADP yielded a much smaller fraction of fast enzyme (∼35%). These observations are discussed on the basis of the structural relationships between the known cholate-binding site and the binuclear cytochrome a3-CuB site: variation in the occupancy of this binding site with cholate or nucleotides may modify reactivity of the oxidized binuclear centre towards cyanide.

Key words. Mitochondrial particles; cytochrome oxidase; fast and slow conformation; cyanide binding; nucleotides; cholate; structure. 

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Copyright information

© Birkhäuser Verlag Basel, 2000

Authors and Affiliations

  • K. Shoji
    • 1
  • A. Giuffrè
    • 2
  • E. D’Itri
    • 2
  • K. Hagiwara
    • 1
  • T. Yamanaka
    • 1
  • M. Brunori*
    • 2
  • P. Sarti
    • 2
  1. 1.Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, Kanda-Surugadai 1-5, Chiyoda-ku, Tokyo 101-8308 (Japan)JP
  2. 2.Department of Biochemical Sciences and CNR Center of Molecular Biology, University of Rome “La Sapienza”, Piazzale Aldo Moro 5, I-00185 (Rome, Italy), Fax +39 06 4440062, e-mail: maurizio.brunori@uniroma1.itIT

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