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Potentiometric study of cytochrome-c1aa3 from thermus-thermophilus

Academic Article
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Overview

authors

  • Yoshida, T.
  • Fee, James

publication date

  • 1985

journal

  • Journal of Inorganic Biochemistry  Journal

abstract

  • We have examined the redox behavior of the cytochrome c1aa3 complex from Thermus thermophilus. In potentiometric titrations the cytochrome c behaves as an independent center having n = 1 and E = 205 mV (NHE). Under the assumption that the individual centers equilibrate independently in this experiment, changes in the absorption band at 603 nm have been resolved into two components: cytochrome a (n = 1, Em = 270 mV, 60% spectral contribution) and cytochrome a3 (n = 2, Em = 360 mV, 40% spectral contribution). The n = 2 process was attributed to strong chemical coupling between cytochrome a3 and CuB. The enzyme was also titrated with a mixture of NADH and PMS, and the results are shown not to conform to a model of intramolecular equilibrium according to the equilibrium constants obtained from the potentiometric titration. It is suggested that a conformational equilibrium within the complex may control electron transfer between cytochromes a and a3.

subject areas

  • Electrochemistry
  • Electron Spin Resonance Spectroscopy
  • Electron Transport Complex IV
  • Methylphenazonium Methosulfate
  • NAD
  • Oxidation-Reduction
  • Potentiometry
  • Spectrophotometry
  • Thermus
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Identity

International Standard Serial Number (ISSN)

  • 0162-0134

Digital Object Identifier (DOI)

  • 10.1016/0162-0134(85)85036-4

PubMed ID

  • 2991468
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Additional Document Info

start page

  • 279

end page

  • 288

volume

  • 23

issue

  • 3-4

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