Cytochrome c oxidase depleted of subunit III: proton-pumping, respiratory control, and pH dependence of the midpoint potential of cytochrome a

1985 ◽  
Vol 23 (3-4) ◽  
pp. 357-364 ◽  
Author(s):  
Debra A. Thompson ◽  
Linda Gregory ◽  
Shelagh Ferguson-Miller
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Ph Dependence ◽  
Respiratory Control ◽  
Proton Pumping ◽  
Midpoint Potential ◽  
Subunit Iii

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.

Effect of subunit III removal on control of cytochrome c oxidase activity by pH

Biochemistry ◽  
1988 ◽  
Vol 27 (17) ◽  
pp. 6307-6314 ◽  
Author(s):  
Linda C. Gregory ◽  
Shelagh Ferguson-Miller
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Oxidase Activity ◽  
Subunit Iii
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