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Transient electron-transfer studies on the two-subunit cytochrome c oxidase from Paracoccus denitrificans

Stowell, Michael H. B. and Larsen, Randy W. and Winkler, Jay R. and Rees, Douglas C. and Chan, Sunney I. (1993) Transient electron-transfer studies on the two-subunit cytochrome c oxidase from Paracoccus denitrificans. Journal of Physical Chemistry, 97 (12). pp. 3054-3057. ISSN 0022-3654. doi:10.1021/j100114a036.

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Intermolecular electron transfer between c-type cytochromes (equine cytochrome c_(550), P. denitrifcans c_(550), and P. denitrificans detergent solubilized membrane-associated c_(552)) and the two-subunit cytochrome c oxidase from P. denitrificans has been studied using a photoinitiated uroporphyrin/NADH reduction system. In the presence of cytochrome c oxidase, the oxidation of transiently produced soluble ferrocytochrome c_(550)’s was biphasic with a fast phase k_(obs) between 80 and 90 s^(-1). The simultaneous reduction of cytochrome a occurred with a k(obs) of 50 s^(-1), suggesting that cytochrome a is not the immediate electron acceptor for these soluble cytochromes. In contrast, the membrane-associated cytochrome c_(552) was not capable of transferring electrons to cytochrome c oxidase, either transiently or under steady-state conditions. It is concluded that the soluble and membrane-associated cytochrome c’s utilize separate electron-transfer pathways into P. denitrifcans cytochrome c oxidase.

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URLURL TypeDescription DOIArticle
Winkler, Jay R.0000-0002-4453-9716
Rees, Douglas C.0000-0003-4073-1185
Chan, Sunney I.0000-0002-5348-2723
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Additional Information:© 1993 American Chemical Society. Received: November 23, 1992. Contribution No. 8722 from the Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA. This work was supported by Grant GM22432 from the National Institute of General Medical Science, U.S.P.H.S. Portions described at the ASBMB/Biophysical Society Joint Meeting. FASEB J. 1992, 6, A284. We thank Siegfried M. Musser and Dr. Theodore J. DiMagno for helpful discussions and critically reviewing this manuscript. We also thank Dr. Thomas Harrold and Larry Tudor for expert assistance in the growth of P. denitrificans.
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National Institute of General Medical SciencesUNSPECIFIED
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Caltech Division of Chemistry and Chemical Engineering8722
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Official Citation:Transient electron-transfer studies on the two-subunit cytochrome c oxidase from Paracoccus denitrificans Michael H. B. Stowell, Randy W. Larsen, Jay R. Winkler, Douglas C. Rees, and Sunney I. Chan The Journal of Physical Chemistry 1993 97 (12), 3054-3057
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Deposited On:08 Feb 2015 02:37
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