scholarly journals The effects of lipid phase transitions on the interaction of mitochondrial NADH–ubiquinone oxidoreductase with ubiquinol–cytochrome c oxidoreductase

1979 ◽  
Vol 178 (2) ◽  
pp. 415-426 ◽  
Author(s):  
C Heron ◽  
M G Gore ◽  
C I Ragan
Keyword(s):  
Cytochrome C ◽  
Cytochrome B ◽  
Complex I ◽  
Complex Iii ◽  
Molar Ratio ◽  
Lipid Phase ◽  
Oxidoreductase Activity ◽  
Arrhenius Plots ◽  
Nadh Cytochrome ◽  
Ubiquinone 10

1. The endogenous phosphatidylcholine and phosphatidylethanolamine of Complexes I and III from bovine heart mitochondria may be completely replaced with 1,2-ditetradecanoyl-sn-glycero-3-phosphocholine with at least partial retention of activity. 2. The lipid-replaced enzymes associate in 1:1 molar ratio to give a Complex I–III unit catalysing NADH-cytochrome c oxidoreductase activity. 3. On increasing the concentration of ubiquinone-10 and the synthetic phospholipid, the lipid-replaced Complexes appear to operate independently of each other as in the natural membrane. Thus the lipid-replaced enzymes associate in exactly the same ways as the enzymes containing natural phospholipids. 4. Arrhenius plots of NADH–cytochrome c oxidoreductase activity reconstituted from lipid-replaced Complexes I and III exhibit changes in slope at 24 degrees C. When the concentrations of phospholipid and ubiquinone-10 are increased, the Arrhenius plots show discontinuities at 24 degrees C as well as changes in slope. 5. The kinetics of cytochrome b reduction by NADH were measured in mixtures containing 2 mol of Complex III/mol of Complex I. When the enzymes contained natural phospholipids. the reduction kinetics were biphasic. When the enzymes had been supplemented with further phospholipid and ubiquinone-10 the kinetics were monophasic. When lipid-replaced enzymes were supplemented with 1,2-ditetradecanoyl-sn-glycero-3-phosphocholine and ubiquinone-10, reduction of cytochrome b was monophasic above the phase-transition temperature of the lipid but biphasic below it. 6. These findings are interpreted in terms of the model for the interaction of Complexes in the natural membrane proposed by Heron, Ragan & Trum-power [(1978) Biochem. J. 174, 791–800].

scholarly journals The interaction between mitochondrial NADH-ubiquinone oxidoreductase and ubiquinol-cytochrome c oxidoreductase. Evidence for stoicheiometric association

1978 ◽  
Vol 174 (3) ◽  
pp. 783-790 ◽  
Author(s):  
C I Ragan ◽  
C Heron
Keyword(s):  
Cytochrome C ◽  
Complex I ◽  
Structural Features ◽  
Complex Iii ◽  
Molar Ratio ◽  
Oxidoreductase Activity ◽  
Ubiquinone Oxidoreductase ◽  
Nadh Ubiquinone Oxidoreductase ◽  
Cytochrome C Reduction ◽  
Nadh Cytochrome

1. The NADH-ubiquinone oxidoreductase complex (Complex I) and the ubiquinol-cytochrome c oxidoreductase complex (Complex III) combine in a 1:1 molar ratio to give NADH-cytochrome c oxidoreductase (Complex I-Complex III). 2. Experiments on the inhibition of the NADH-cytochrome c oxidoreductase activity of mixtures of Complexes I and III by rotenone and antimycin indicate that electron transfer between a unit of Complex I-Complex III and extra molecules of Complexes I or III does not contribute to the overall rate of cytochrome c reduction. 3. The reduction by NADH of the cytochrome b of mixtures of Complexes I and III is biphasic. The extents of the fast and slow phases of reduction are determined by the proportion of the total Complex III specifically associated with Complex I. 4. Activation-energy measurements suggest that the structural features of the Complex I-Complex III unit promote oxidoreduction of endogenous ubiquinone-10.

scholarly journals Effects of proteolytic digestion by chymotrypsin on the structure and catalytic properties of reduced nicotinamide–adenine dinucleotide–ubiquinone oxidoreductase from bovine heart mitochondria

1977 ◽  
Vol 165 (2) ◽  
pp. 295-301 ◽  
Author(s):  
Susan E. Crowder ◽  
C. Ian Ragan
Keyword(s):  
Complex I ◽  
Time Course ◽  
Nadh Dehydrogenase ◽  
Sodium Dodecyl ◽  
Complex Iii ◽  
Type Ii ◽  
Oxidoreductase Activity ◽  
Ubiquinone Oxidoreductase ◽  
Nadh Cytochrome ◽  
Reduced Nicotinamide Adenine Dinucleotide

1. Incubation of NADH–ubiquinone oxidoreductase (Complex I) with chymotrypsin caused loss of rotenone-sensitive ubiquinone-1 reduction and an increase in rotenone-insensitive ubiquinone reduction. 2. Within the same time-course, NADH–K3Fe(CN)6 oxidoreductase activity was unaffected. 3. Mixing of chymotrypsin-treated Complex I with Complex III did not give rise to NADH–cytochrome c oxidoreductase activity. 4. Gel electrophoresis in the presence of sodium dodecyl sulphate revealed selective degradation of several constituent polypeptides by chymotrypsin. 5. With higher chymotrypsin concentrations and longer incubation times, a decrease in NADH–K3Fe(CN)6 oxidoreductase was observed. The kinetics of this decrease correlated with solubilization of the low-molecular-weight type-II NADH dehydrogenase (subunit mol.wts. 53000 and 27000) and with degradation of a polypeptide of mol.wt. 30000. 6. Phospholipid-depleted Complex I was more rapidly degraded by chymotrypsin. Specifically, a subunit of mol.wt. 75000, resistant to chymotrypsin in untreated Complex I, was degraded in phospholipid-depleted Complex I. In addition, the 30000-mol.wt. polypeptide was also more rapidly digested, correlating with an increased rate of transformation to type II NADH dehydrogenase.

scholarly journals Cytochrome c-mediated electron transfer between ubiquinol-cytochrome c reductase and cytochrome c oxidase. Kinetic evidence for a mobile cytochrome c pool

1984 ◽  
Vol 217 (2) ◽  
pp. 551-560 ◽  
Author(s):  
R J Froud ◽  
C I Ragan
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
State Level ◽  
Complex Iii ◽  
Molar Ratio ◽  
Cytochrome C Reductase ◽  
Molar Ratios ◽  
Ubiquinol Oxidase ◽  
Mediated Electron Transfer ◽  
Pool Model

Ubiquinol oxidase has been reconstituted from ubiquinol-cytochrome c reductase (Complex III), cytochrome c and cytochrome c oxidase (Complex IV). The steady-state level of reduction of cytochrome c by ubiquinol-2 varies with the molar ratios of the complexes and with the presence of antimycin in a way that can be quantitatively accounted for by a model in which cytochrome c acts as a freely diffusible pool on the membrane. This model was based on that of Kröger & Klingenberg [(1973) Eur. J. Biochem. 34, 358-368] for ubiquinone-pool behaviour. Further confirmation of the pool model was provided by analysis of ubiquinol oxidase activity as a function of the molar ratio of the complexes and prediction of the degree of inhibition by antimycin.

A mitochondrial cytochrome b mutation but no mutations of nuclearly encoded subunits in ubiquinol cytochrome c reductase (complex III) deficiency

1999 ◽  
Vol 104 (6) ◽  
pp. 460-466 ◽  
Author(s):  
Isabelle Valnot ◽  
Johanna Kassis ◽  
Dominique Chretien ◽  
Pascale de Lonlay ◽  
Béatrice Parfait ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome B ◽  
Complex Iii ◽  
Mitochondrial Cytochrome ◽  
Cytochrome C Reductase ◽  
Mitochondrial Cytochrome B

scholarly journals The reconstitution of l-3-glycerophosphate-cytochrome c oxidoreductase from l-3-glycerophosphate dehydrogenase, ubiquinone-10 and ubiquinol—cytochrome c oxidoreductase

1980 ◽  
Vol 192 (1) ◽  
pp. 19-31 ◽  
Author(s):  
I R Cottingham ◽  
C I Ragan
Keyword(s):  
Cytochrome C ◽  
Nadh Dehydrogenase ◽  
Brain Mitochondria ◽  
Complex Iii ◽  
Protein Ratio ◽  
Bovine Heart ◽  
Glycerophosphate Dehydrogenase ◽  
Reconstituted System ◽  
Ubiquinone 10 ◽  
Self Aggregation

Purified L-3-glycerophosphate dehydrogenase from pig brain mitochondria interacts with ubiquinone-10 and ubiquinol-cytochrome c oxidoreductase (Complex III) from bovine heart mitochondria to reconstitute antimycin-sensitive L-3-glycerophosphate- cytochrome c oxidoreductase. This activity is completely dependent on the two enzymes and largely dependent on ubiquinone-10. Reconstitution requires that the two enzymes should be simultaneously present in the same membranous aggregate produced by removal of detergent from the enzymes. Reconstitution by removing detergent by dialysis or dilution is inefficient because of self-aggregation of the dehydrogenase. Highly efficient reconstitution can be achieved if the enzymes are co-precipitated by addition of ethanol. The rate with reconstituted enzyme approaches that expected from the turnover of the dehydrogenase with ubiquinone-1 as acceptor. The behaviour of the reconstituted system shows some of the characteristics expected for a stoicheiometric association of one molecule of dehydrogenase with one molecule of Complex III. On raising the phospholipid/protein ratio, the dehydrogenase and Complex III appear to operate as independent enzymes acting in sequence. These effects are very similar to those observed for the interaction of NADH dehydrogenase and Complex III and are explained in terms of the model proposed by Heron, Ragan & Trumpower [(1978) biochem. J. 174, 791-800].

Aerobic and anaerobic respiratory systems in Campylobacter fetus subsp. jejuni grown in atmospheres containing hydrogen

1982 ◽  
Vol 152 (1) ◽  
pp. 306-314
Author(s):  
G M Carlone ◽  
J Lascelles
Keyword(s):  
Cytochrome C ◽  
Cytochrome B ◽  
System Analysis ◽  
Maximum Growth ◽  
Oxidoreductase Activity ◽  
Intact Cells ◽  
Cytochrome O ◽  
Campylobacter Fetus ◽  
Fetus Subsp ◽  
Carbon Monoxide Binding

Maximum growth of Campylobacter fetus subsp. jejuni, strain C-61, occurred when the cultures were incubated with shaking in atmospheres containing approximately 30% hydrogen, 5% oxygen, and 10% CO2. Suspensions of cells grown under these conditions consumed oxygen with formate as the substrate in the presence of 0.33 mM cyanide, which completely inhibited respiration with ascorbate-N,N,N',N'-tetramethyl-p-phenylenediamine and with lactate. Spectroscopic evidence with intact cells suggested that a form of cytochrome c, reducible with formate but not with lactate or ascorbate-N,N,N',N'-tetramethyl-p-phenylenediamine, can be reoxidized by a cyanide-insensitive system. Analysis of membranes from the cells showed high- and low-potential forms of cytochrome c, cytochrome b, and various enzymes, including hydrogenase, formate dehydrogenase, and fumarate reductase. The predominant carbon monoxide-binding pigment appeared to be a form of cytochrome c, but the spectra also showed evidence of cytochrome o. The membrane cytochromes were reduced by hydrogen in the presence of 2-heptyl-4-hydroxyquinoline-N-oxide at concentrations which prevented the reduction of cytochrome c with succinate as the electron donor. Reoxidation of the substrate-reduced cytochromes by oxygen was apparently mediated by cyanide-sensitive and cyanide-insensitive systems. The membranes also had hydrogen-fumarate oxidoreductase activity mediated by cytochrome b. We conclude that C. fetus jejuni has high- and low-potential forms of cytochrome which are associated with a complex terminal oxidase system.

Increased peak oxygen consumption of trained muscle requires increased electron flux capacity

1994 ◽  
Vol 77 (4) ◽  
pp. 1941-1952 ◽  
Author(s):  
D. M. Robinson ◽  
R. W. Ogilvie ◽  
P. C. Tullson ◽  
R. L. Terjung
Keyword(s):  
Electron Transport ◽  
Cytochrome C ◽  
Reductase Activity ◽  
Tight Binding ◽  
Treadmill Running ◽  
Complex Iii ◽  
Peak Oxygen Consumption ◽  
Transport Capacity ◽  
Cytochrome C Reductase ◽  
Nadh Cytochrome

The importance of the training-induced increase in mitochondrial capacity in realizing the increase in maximal O2 consumption (VO2max) of trained muscle was evaluated using an isolated perfused rat hindlimb preparation at a high blood flow (approximately 80 ml.min-1.100 g-1) during tetanic contractions. Rats trained for 8-–12 wk by treadmill running exhibited an approximately 25% increase in muscle VO2max (5.62 +/- 0.31 to 7.06 +/- 0.64 mumol.min-1.g-1), an increase in mitochondrial enzyme activity (approximately 70% for cytochrome oxidase and approximately 55% for NADH cytochrome-c reductase), and an increase in tissue capillarity (14%) that is expected to increase the O2 exchange capacity of the tissue. Muscle VO2max of sedentary (n = 34) and trained (n = 30) animals was determined, and electron transport capacity was acutely managed with myxothiazol, a tight-binding inhibitor of complex III. Inhibition of complex III was similar among 1) the low- and high-oxidative fibers and 2) the superficial and deep mitochondrial populations within muscle. Inhibition of NADH cytochrome-c reductase activity resulted in reductions in muscle VO2max with similar dose responses (mean effective dose of approximately 0.2 microM) of myxothiazol added to the perfusion medium. The extraction of O2 by the contracting muscle decreased as VO2max declined. The increase in muscle VO2max observed in the muscle of trained animals was eliminated when its electron transport capacity was reduced to that observed in normal sedentary rat muscle. Thus, the exercise-induced adaptation of an increased muscle mitochondrial content appears to be essential for trained muscle to exhibit its increased O2 flux capacity. The results of the present experiment illustrate the importance of mitochondrial adaptations in muscle remodeled by exercise training.

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