کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8299240 | 1537052 | 2008 | 9 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
The dimeric structure of the cytochrome bc1 complex prevents center P inhibition by reverse reactions at center N
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کلمات کلیدی
موضوعات مرتبط
علوم زیستی و بیوفناوری
علوم کشاورزی و بیولوژیک
دانش گیاه شناسی
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چکیده انگلیسی
Energy transduction in the cytochrome bc1 complex is achieved by catalyzing opposite oxido-reduction reactions at two different quinone binding sites. We have determined the pre-steady state kinetics of cytochrome b and c1 reduction at varying quinol/quinone ratios in the isolated yeast bc1 complex to investigate the mechanisms that minimize inhibition of quinol oxidation at center P by reduction of the bH heme through center N. The faster rate of initial cytochrome b reduction as well as its lower sensitivity to quinone concentrations with respect to cytochrome c1 reduction indicated that the bH hemes equilibrated with the quinone pool through center N before significant catalysis at center P occurred. The extent of this initial cytochrome b reduction corresponded to a level of bH heme reduction of 33%-55% depending on the quinol/quinone ratio. The extent of initial cytochrome c1 reduction remained constant as long as the fast electron equilibration through center N reduced no more than 50% of the bH hemes. Using kinetic modeling, the resilience of center P catalysis to inhibition caused by partial pre-reduction of the bH hemes was explained using kinetics in terms of the dimeric structure of the bc1 complex which allows electrons to equilibrate between monomers.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Biochimica et Biophysica Acta (BBA) - Bioenergetics - Volume 1777, Issues 7â8, JulyâAugust 2008, Pages 1044-1052
Journal: Biochimica et Biophysica Acta (BBA) - Bioenergetics - Volume 1777, Issues 7â8, JulyâAugust 2008, Pages 1044-1052
نویسندگان
Raul Covian, Bernard L. Trumpower,