Regulation of electron flux through cytochrome c oxidase: pH, ΔpH and fatty acids

1993 ◽  
Vol 21 (3) ◽  
pp. 781-784 ◽  
Author(s):  
John M. Wrigglesworth ◽  
Martyn A. Sharpe ◽  
Chris E. Cooper
Keyword(s):  
Fatty Acids ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Electron Flux

scholarly journals Chlorpromazine and carnitine-dependency of rat liver peroxisomal β-oxidation of long-chain fatty acids

1987 ◽  
Vol 241 (3) ◽  
pp. 783-791 ◽  
Author(s):  
J Vamecq
Keyword(s):  
Fatty Acids ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Rat Liver ◽  
Fatty Acyl ◽  
Carnitine Palmitoyltransferase ◽  
Acid Oxidation ◽  
Synthetase Activity ◽  
Mitochondrial Fatty Acid Oxidation ◽  
Mitochondrial Fatty Acid

The enzyme targets for chlorpromazine inhibition of rat liver peroxisomal and mitochondrial oxidations of fatty acids were studied. Effects of chlorpromazine on total fatty acyl-CoA synthetase activity, on both the first and the third steps of peroxisomal beta-oxidation, on the entry of fatty acyl-CoA esters into the peroxisome and on catalase activity, which allows breakdown of the H2O2 generated during the acyl-CoA oxidase step, were analysed. On all these metabolic processes, chlorpromazine was found to have no inhibitory action. Conversely, peroxisomal carnitine octanoyltransferase activity was depressed by 0.2-1 mM-chlorpromazine, which also inhibits mitochondrial carnitine palmitoyltransferase activity in all conditions in which these enzyme reactions are assayed. Different patterns of inhibition by the drug were, however, demonstrated for both these enzyme activities. Inhibitory effects of chlorpromazine on mitochondrial cytochrome c oxidase activity were also described. Inhibitions of both cytochrome c oxidase and carnitine palmitoyltransferase are proposed to explain the decreased mitochondrial fatty acid oxidation with 0.4-1.0 mM-chlorpromazine reported by Leighton, Persico & Necochea [(1984) Biochem. Biophys. Res. Commun. 120, 505-511], whereas depression by the drug of carnitine octanoyltransferase activity is presented as the factor responsible for the decreased peroxisomal beta-oxidizing activity described by the above workers.

scholarly journals A Cytochrome c Oxidase Model Catalyzes Oxygen to Water Reduction Under Rate-Limiting Electron Flux

Science ◽  
2007 ◽  
Vol 315 (5818) ◽  
pp. 1565-1568 ◽  
Author(s):  
J. P. Collman ◽  
N. K. Devaraj ◽  
R. A. Decreau ◽  
Y. Yang ◽  
Y.-L. Yan ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Electron Flux ◽  
Water Reduction ◽  
Rate Limiting

scholarly journals The effect of non-esterified fatty acids on the proton-pumping cytochrome c oxidase reconstituted into liposomes

1988 ◽  
Vol 254 (1) ◽  
pp. 139-145 ◽  
Author(s):  
N Labonia ◽  
M Müller ◽  
A Azzi
Keyword(s):  
Fatty Acids ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Respiratory Control ◽  
Proton Pumping ◽  
Phospholipid Vesicles ◽  
Proton Permeability ◽  
Enzyme Preparations ◽  
Esterified Fatty Acids ◽  
Subunit Iii

Bovine heart cytochrome c oxidase was reconstituted in phospholipid vesicles, and the effect of different non-esterified fatty acids (NEFA) was studied on its proton pump and on the proton permeability of the vesicles. Neither parameter appeared to be affected by concentrations of NEFA known to uncouple oxidative phosphorylation (10 microM). Also the permeability for K+ was not affected by them. The fatty acids caused an increase in the rate of electron transfer in the absence, but not in the presence, of uncoupler and/or valinomycin [diminution of the respiratory-control index (RCI)]. The RCI of 8.7-7.5 was decreased to about 4.5 in the presence of 0.27-10 microM-NEFA. Oleic acid was not effective at the above concentrations. Subunit III-depleted enzyme preparations gave vesicles with an RCI of about 5.5, which was decreased to 4.5 in the presence of NEFA. With both native and subunit III-depleted oxidase the RCI was never decreased to the value of 1 by NEFA, as happens with classical protonophores.

scholarly journals Fatty acids as modulators of cytochrome c oxidase in proteoliposomes

1996 ◽  
Vol 320 (2) ◽  
pp. 557-561 ◽  
Author(s):  
Martyn SHARPE ◽  
Ivano PERIN ◽  
John WRIGGLESWORTH ◽  
Peter NICHOLLS
Keyword(s):  
Fatty Acids ◽  
Enzyme Activity ◽  
Oleic Acid ◽  
Membrane Potential ◽  
Cytochrome C ◽  
Palmitic Acid ◽  
Cytochrome C Oxidase ◽  
Respiratory Control ◽  
Similar Concentration

The control of cytochrome c oxidase turnover in proteoliposomes by membrane potential (ΔΨ) and by pH gradient (ΔpH) is probably kinetic in nature, and inhibition by valinomycin and stimulation by nigericin indicate that ΔpH exerts a greater influence than does an equivalent ΔΨ. Oleic acid at 100 µM removes all ΔΨ and ΔpH control, whereas a similar concentration of palmitic acid increases turnover but does not completely abolish control. Valinomycin acts synergistically with both fatty acids, indicating that the latter can act as H+/K+ exchangers, but neither fatty acid alone markedly affects ΔpH, showing that they cannot fully mimic nigericin. Oleate, but not palmitate, diminishes ΔΨ, and can move electrophoretically as oleate anion. Submicromolar palmitic acid concentrations partly stimulate turnover in ΔΨ- and ΔpH-controlled proteoliposomes, as reported by Labonia, Muller and Azzi [(1988) Biochem. J. 254, 130–145], which might represent a direct effect on cytochrome c oxidase. The ubiquity of fatty acids in biological membranes suggests that these substances might be responsible for limiting respiratory control and enzyme activity in vivo.

Ligation, inhibition, and activation of cytochrome c oxidase by fatty acids

1997 ◽  
Vol 75 (1) ◽  
pp. 71-79 ◽  
Author(s):  
M Sharpe ◽  
I Perin ◽  
B Tattrie ◽  
P Nicholls
Keyword(s):  
Fatty Acids ◽  
Cytochrome C ◽  
Cytochrome C Oxidase

Role of phospholipid fatty acids on the kinetics of high and low affinity sites of cytochrome c oxidase

1986 ◽  
Vol 64 (11) ◽  
pp. 1195-1210 ◽  
Author(s):  
A. Trivedi ◽  
D. J. Fantin ◽  
E. Reno Tustanoff
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Membrane Fluidity ◽  
Mitochondrial Membrane ◽  
Polar Head Group ◽  
Mitochondrial Membranes ◽  
Inner Mitochondrial Membrane ◽  
High Affinity

The nature of the interactions between cytochrome c oxidase and the phospholipids in mitochondrial membranes has been investigated by varying the nature of the fatty acyl components of Saccharomyces cerevisiae. A double fatty acid yeast mutant, FAI-4C, grown in combinations of unsaturated (oleic, linoleic, linolenic, and eicosenoic) and saturated (lauric and palmitic) fatty acids, was employed to modify mitochondrial membranes. The supplemented fatty acids constituted a unique combination of different acyl chain lengths with varying degrees of unsaturation which were subsequently incorporated into mitochondrial phospholipids. Phosphatidylethanolamine and cardiolipin, the predominant phospholipids of the inner mitochondrial membrane, were characterized by their high levels of supplemented unsaturated fatty acids. Increasing the chain length or the degree of unsaturation of mitochondrial membrane phospholipids had no effect on altering the nature of the phospholipid polar head group but did result in a profound change on the specific activity of cytochrome c oxidase. When studied under conditions of different ionic strengths and pHs the enzyme's activity, as documented by Eadie–Hofstee plots, showed biphasic kinetics. The kinetic parameters for the low affinity reaction were greatly influenced by the changes in the membrane fatty acids and only marginal effects were noted at the high affinity reaction site. The discontinuities in the steady-state fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene, monitored at increasing temperatures, suggested that changes in membrane fluidity were conditioned by alterations in mitochondrial membrane fatty acid constituents. These results indicate that the lipid changes affecting the low affinity binding site of cytochrome c oxidase may be the result of lipid–protein interactions which lead to enzyme conformational changes or may be due to gross changes in membrane fluidity. It may, therefore, follow that this enzyme site may be embedded in or be juxtaposed to the outer surface of the inner mitochondrial membrane bilayer in contrast to the high affinity site which has been shown to be significantly above the membrane plane.

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