Electron transfer by domain movement in cytochrome bc1

Zhaolei Zhang, Lishar Huang, Vladimir M. Shulmeister, Young In Chi, Kyeong Kyu Kim, Li Wei Hung, Antony R. Crofts, Edward A. Berry, Sung Hou Kim

Research output: Contribution to journalReview articlepeer-review

970 Scopus citations


The cytochrome bc1 is one of the three major respiratory enzyme complexes residing in the inner mitochondrial membrane. Cytochrome bc1 transfers electrons from ubiquinol to cytochrome c and uses the energy thus released to form in electrochemical gradient across the inner membrane. Our X-ray crystal structure of the complex from chicken, cow and rabbit in both the presence and absence of inhibitors of quinone oxidation, reveal two different locations for the extrinsic domain of one component of the enzyme, an iron-sulphur protein. One location is close enough to the supposed quinol oxidation site to allow reduction of the Fe-S protein by ubiquinol. The other site is close enough to cytochrome c1 to allow oxidation of the Fe-S protein by the cytochrome. As neither location will allow both reactions to proceed at a suitable rate, the reaction mechanism must involve movement of the extrinsic domain of the Fe-S component in order to shuttle electrons from ubiquinol to cytochrome c1. Such a mechanism has not previously been observed in redox protein complexes.

Original languageEnglish (US)
Pages (from-to)677-684
Number of pages8
Issue number6677
StatePublished - Apr 16 1998
Externally publishedYes


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