The triphasic reduction of cytochrome b in the succinate-cytochrome c reductase

Jin, Yuan-Zhen; Tang, Hai-Lun; Shulian, Li; Tsou, Chen‐Lu

doi:10.1016/0005-2728(81)90063-3

Cited by 26 publications

(4 citation statements)

References 6 publications

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“…After further incubation for 8 min, cytochrome q was completely reduced while cytochrome b again became partially reduced. This triphasic reduction of cytochrome b has been explained by classical shemes for the Q cycle (Hatefi, 1985) and was initially reported by Jin et al (1981). The kinetics of reduction of cytochrome b were reported in our earlier publication (Beattie & Clejan, 1986).…”

Section: Resultssupporting

confidence: 61%

Reduction of cytochrome b in mitochondria from yeast lacking coenzyme Q

Clejan¹,

Beattie²

1986

Biochemistry

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Mitochondria isolated from coenzyme Q deficient yeast cells had no detectable NADH:cytochrome c reductase or succinate:cytochrome c reductase but had comparable amounts of cytochromes b and c1 as wild-type mitochondria. Addition of succinate to the mutant mitochondria resulted in a slight reduction of cytochrome b; however, the subsequent addition of antimycin resulted in a biphasic reduction of cytochrome b, leading to reduction of 68% of the total dithionite-reducible cytochrome b. No "red" shift in the absorption maximum was observed, and no cytochrome c1 was reduced. The addition of either myxothiazol or alkylhydroxynaphthoquinone blocked the reduction of cytochrome b observed with succinate and antimycin, suggesting that the reduction of cytochrome b-562 in the mitochondria lacking coenzyme Q may proceed by a pathway involving cytochrome b at center o where these inhibitors block. Cyanide did not prevent the reduction of cytochrome b by succinate and antimycin the the mutant mitochondria. These results suggest that the succinate dehydrogenase complex can transfer electrons directly to cytochrome b in the absence of coenzyme Q in a reaction that is enhanced by antimycin. Reduced dichlorophenolindophenol (DCIP) acted as an effective bypass of the antimycin block in complex III, resulting in oxygen uptake with succinate in antimycin-treated mitochondria. By contrast, reduced DCIP did not restore oxygen uptake in the mutant mitochondria, suggesting that coenzyme Q is necessary for the bypass. The addition of low concentrations of DCIP to both wild-type and mutant mitochondria reduced with succinate in the presence of antimycin resulted in a rapid oxidation of cytochrome b perhaps by the pathway involving center o, which does not require coenzyme Q.

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Section: Resultssupporting

confidence: 61%

Reduction of cytochrome b in mitochondria from yeast lacking coenzyme Q

Clejan¹,

Beattie²

1986

Biochemistry

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“…Much of the evidence supporting the Q cycle was gathered from examining the pre-steady-state reduction of cytochromes b and cl in mitochondria. One such example is the triphasic nature of cytochrome b reduction (74). When electrons are delivered to the fully oxidized cytochrome bec complex from ubiquinol, cytochrome cl is reduced in an essentially linear manner.…”

Section: Mechanism Of Electron Transfer and Energy Transductionmentioning

confidence: 99%

Cytochrome bc1 complexes of microorganisms.

Trumpower

1990

Microbiological Reviews

203

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Nostoc spp. Photosynthetic, filamentous cyanobacterium 79 ganisms which have alternate electron transfer pathways in addition to a bc, complex, nor do they effectively inhibit the bf complex. Consequently, lack of sensitivity to these bc1 inhibitors does not preclude the involvement of a bc1 or bf complex in the electron transfer pathways of the microorganism., In Table 1 I have listed procaryotes that have been shown to contain a bc1 or bfcomplex. The complexes have not been purified from many of these species. Therefore, I have taken as evidence for the existence of a bc, or bf complex the presence of a Rieske-type iron-sulfur protein along with membranous band c-type cytochromes, the isolation of genes encoding these proteins characteristic of the bc1 or bf complexes, or the demonstration of antimycinor myxothiazol-sensitive electron transfer.

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“…Then the second electron of ubiquinol is passed through the ''low-potential chain'' consisting of cytochromes b L and b H , to reduce ubiquinone or ubisemiquinone bound at the quinol reduction site (Qn) [13,14]. Pre-steady state kinetic analysis of cytochrome b L and ISP indicates that both are reduced by ubiquinol at the same rate and the reduction of b H occurs before the reduction of cytochrome c 1 [15][16][17][18]. Since the reduction of ISP by QH 2 takes place when the head domain of ISP is located at the b-position, a movement of head domain to the c 1 -position is necessary for transfer electron to cytochrome c 1 .…”

Section: Introductionmentioning

confidence: 99%

“…It was speculated that protein conformational changes caused by electron transfer from cytochrome b L to b H facilitates the movement of the head domain of ISP [18][19][20]. This speculation is supported by the fact that reduction of cytochrome b H occurs before the reduction of cytochrome c 1 [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Domain movement of iron sulfur protein in cytochrome bc₁ complex is facilitated by the electron transfer from cytochrome b_L to b_H

Cen

2008

FEBS Letters

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The key step of the ''protonmotive Q-cycle'' mechanism for cytochrome bc 1 complex is the bifurcated oxidation of ubiquinol at the Qp site. ISP is reduced when its head domain is at the b-position and subsequent move to the c 1 position, to reduce cytochrome c 1 , upon protein conformational changes caused by the electron transfer from cytochrome b L to b H . Results of analyses of the inhibitory efficacy and the binding affinity, determined by isothermal titration calorimetry, of Pm and Pf, on different redox states of cytochrome bc 1 complexes, confirm this speculation. Pm inhibitor has a higher affinity and better efficacy with the cytochrome b H reduced complex and Pf binds better and has a higher efficacy with the ISP reduced complex.

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The triphasic reduction of cytochrome b in the succinate-cytochrome c reductase

Cited by 26 publications

References 6 publications

Reduction of cytochrome b in mitochondria from yeast lacking coenzyme Q

Reduction of cytochrome b in mitochondria from yeast lacking coenzyme Q

Cytochrome bc1 complexes of microorganisms.

Domain movement of iron sulfur protein in cytochrome bc₁ complex is facilitated by the electron transfer from cytochrome b_L to b_H

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The triphasic reduction of cytochrome b in the succinate-cytochrome c reductase

Cited by 26 publications

References 6 publications

Reduction of cytochrome b in mitochondria from yeast lacking coenzyme Q

Reduction of cytochrome b in mitochondria from yeast lacking coenzyme Q

Cytochrome bc1 complexes of microorganisms.

Domain movement of iron sulfur protein in cytochrome bc1 complex is facilitated by the electron transfer from cytochrome bL to bH

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Domain movement of iron sulfur protein in cytochrome bc₁ complex is facilitated by the electron transfer from cytochrome b_L to b_H