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 Reconstitution of cytochrome c oxidase in phospholipid vesicles containing polyvinylic polymers

1989 ◽  
Vol 257 (3) ◽  
pp. 783-787 ◽  
Author(s):  
P Sarti ◽  
G Antonini ◽  
F Malatesta ◽  
B Vallone ◽  
S Villaschi ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Functional Characterization ◽  
Respiratory Control ◽  
Phospholipid Vesicles ◽  
Lipid Phase ◽  
Protein Orientation ◽  
Highly Hydrophobic ◽  
Polymer Interaction

Cytochrome c oxidase was reconstituted in phospholipid vesicles in the presence of highly hydrophobic poly(vinyl alkanoate) polymers. Electron-microscopy observations demonstrated that polymer interaction with the lipid phase induces vesicles to adopt smaller diameters than those typical of standard proteoliposomes. Functional characterization of these polymer-proteoliposome structures indicates that the reconstitution of the enzyme proceeds efficiently without causing either scrambling of the protein orientation in the membrane or loss of respiratory control. A clear dependence of respiratory control ratio on vesicle size was also demonstrated, which is in agreement with a previous model proposed for control of activity of cytochrome c oxidase vesicles [Brunori, Sarti, Colosimo, Antonini, Malatesta, Jones & Wilson (1985) EMBO J. 4, 2365-2368].

scholarly journals 1K1115 Proton pumping activity and resonance Raman spectra of cytochrome c oxidase reconstituted in phospholipid vesicles

2002 ◽  
Vol 42 (supplement2) ◽  
pp. S62
Author(s):  
M. Aki ◽  
Sang-Choul Im ◽  
S. Kuroiwa ◽  
T. Ogura ◽  
E. Katayama ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Raman Spectra ◽  
Resonance Raman ◽  
Proton Pumping ◽  
Phospholipid Vesicles ◽  
Resonance Raman Spectra ◽  
Pumping Activity

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.

scholarly journals Ionic-strength-dependence of the oxidation of native and pyridoxal 5′-phosphate-modified cytochromes c by cytochrome c oxidase

1989 ◽  
Vol 262 (2) ◽  
pp. 591-596 ◽  
Author(s):  
G Kossekova ◽  
B Atanasov ◽  
R Bolli ◽  
A Azzi
Keyword(s):  
Ionic Strength ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Dimer Formation ◽  
Ionic Strength Dependence ◽  
Enzyme Preparations ◽  
Linear Character ◽  
Cytochromes C ◽  
Charge Interaction ◽  
Subunit Iii

The ionic-strength-dependences of the rate constants (log k plotted versus square root of 1) for oxidation of native and pyridoxal 5′-phosphate-modified cytochromes c by three different preparations of cytochrome c oxidase have complex non-linear character, which may be explained on the basis of present knowledge of the structure of the oxidase and the monomer-dimer equilibrium of the enzyme. The wave-type curve (with a minimum and a maximum) for oxidation of native cytochrome c by purified cytochrome c oxidase depleted of phospholipids may reflect consecutively inhibition of oxidase monomers (initial descending part), competition between this inhibition and dimer formation, resulting in increased activity (second part with positive slope), and finally inhibition of oxidase dimers (last descending part of the curve). The dependence of oxidation of native cytochrome c by cytochrome c oxidase reconstituted into phospholipid vesicles is a curve with a maximum, without the initial descending part described above. This may reflect the lack of pure monomers in the vesicles, where equilibrium is shifted to dimers even at low ionic strength. Subunit-III-depleted cytochrome c oxidase does not exhibit the maximum seen with the other two enzyme preparations. This may mean that removal of subunit III hinders dimer formation. The charge interactions of each of the cytochromes c (native or modified) with the three cytochrome c oxidase preparations are similar, as judged by the similar slopes of the linear dependences at I values above the optimal one. This shows that subunit III and the phospholipid membrane do not seem to be involved in the specific charge interaction of cytochrome c oxidase with cytochrome c.

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