Complex III of Electron Transport Chain: Difference between revisions
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== Q Cycle == | == Q Cycle == | ||
<applet load='1kyo' size='400' color='black' frame='true' align='right' scene ='Complex_III_of_Electron_Transport_Chain/Sma_525_red/2' name='third'/>The cycle starts with the binding of UQH<sub>2</sub>, ubiquinol, to cytochrome b at a Q<sub>P</sub> site. In the applet to the right the Q<sub>P</sub> site is binding <font color=red>stigmatellin</font>. This binding causes the Rieske protein to flex at the hinge region rotating the Fe/S head so that the His which is bound to the Fe/S also binds to the UQH<sub>2</sub> at Q<sub>P</sub>. Binding of the His to UQH<sub>2</sub> reduces its pK, and the quinol loses a proton. The position of Q<sub>P</sub> in the complex is such that the proton which is lost diffuses to the intermembrane space. | <applet load='1kyo' size='400' color='black' frame='true' align='right' scene ='Complex_III_of_Electron_Transport_Chain/Sma_525_red/2' name='third'/>The cycle starts with the binding of UQH<sub>2</sub>, ubiquinol, to cytochrome b at a Q<sub>P</sub> site. In the applet to the right the Q<sub>P</sub> site is binding <font color=red>stigmatellin</font>. This binding causes the Rieske protein to flex at the hinge region rotating the Fe/S head so that the His which is bound to the Fe/S also binds to the <scene name='Complex_III_of_Electron_Transport_Chain/Posit_cytob_closeup/1'>UQH<sub>2</sub> at Q<sub>P</sub></font>. Binding of the His to UQH<sub>2</sub> reduces its pK, and the quinol loses a proton. The position of Q<sub>P</sub> in the complex is such that the proton which is lost <scene name='Complex_III_of_Electron_Transport_Chain/Proton_releas/2'>diffuses to the intermembrane space</font>. | ||
