ISSN:
1573-6881
Keywords:
cytochrome bc 1 complex
;
electron transfer reaction: mitochondrial-processing peptidase
;
superoxide-generation activity
;
electron transfer inhibitors
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Physics
Notes:
Abstract The mitochondrial cytochrome bc 1 complex is a multifunctional membrane protein complex. Itcatalyzes electron transfer, proton translocation, peptide processing, and superoxide generation.Crystal structure data at 2.9 Å resolution not only establishes the location of the redox centersand inhibitor binding sites, but also suggests a movement of the head domain of the iron–sulfurprotein (ISP) during bc 1 catalysis and inhibition of peptide-processing activity during complexmaturation. The functional importance of the movement of extramembrane (head) domain ofISP in the bc 1 complex is confirmed by analysis of the Rhodobacter sphaeroides bc 1 complexmutants with increased rigidity in the ISP neck and by the determination of rate constants foracid/base-induced intramolecular electron transfer between [2Fe–2S] and heme c 1 in nativeand inhibitor-loaded beef complexes. The peptide-processing activity is activated in bovineheart mitochondrial bc 1 complex by nonionic detergent at concentrations that inactivate electrontransfer activity. This peptide-processing activity is shown to be associated with subunits Iand II by cloning, overexpression and in vitro reconstitution. The superoxide-generation siteof the cytochrome bc 1 complex is located at reduced b L and Q•−. The reaction is membranepotential-, and cytochrome c-dependent.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1005411510913
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