Dalmonte 2009 J Biol Chem: Difference between revisions
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Revision as of 14:42, 7 August 2013
Dalmonte ME, Forte E, Genova ML, Giuffrรจ A, Sarti P, Lenaz G (2009) Control of respiration by cytochrome c oxidase in intact cells: role of the membrane potential. J Biol Chem 284: 32331-32335. |
Dalmonte ME, Forte E, Genova ML, Giuffre A, Sarti P, Lenaz G (2009) J Biol Chem
Abstract: Metabolic control analysis was applied to intact HepG2 cells. The effect on the control coefficient of cytochrome c oxidase (CcOX) over cell respiration of both the electrical (ฮฯ) and chemical (ฮpH) component of the mitochondrial transmembrane proton electrochemical gradient (ฮฮผH+) was investigated. The overall O2 consumption and specific CcOX activity of actively phosphorylating cells were titrated with cyanide under conditions in which ฮฯ and ฮpH were selectively modulated by addition of ionophores. In the absence of ionophores, CcOX displayed a high control coefficient (CIV = 0.73), thus representing an important site of regulation of mitochondrial oxidative phosphorylation. A high control coefficient value (CIV = 0.85) was also measured in the presence of nigericin, i.e. when ฮฯ is maximal, and in the presence of nigericin and valinomycin (CIV = 0.77), when ฮฮผH+ is abolished. In contrast, CcOX displayed a markedly lower control coefficient (CIV = 0.30) upon addition of valinomycin, when ฮฯ is converted into ฮpH. These results show that ฮฯ is responsible for the tight control of CcOX over respiration in actively phosphorylating cells. โข Keywords: Nigericin, Valinomycin, Cytochrome C oxidase, Membrane potential
โข O2k-Network Lab: IT Roma Sarti P, IT Bologna Lenaz G
Labels:
Organism: Human, Rat
Tissue;cell: Liver
Preparation: Intact cells
Enzyme: Complex IV; Cytochrome c Oxidase"Complex IV; Cytochrome c Oxidase" is not in the list (Adenine nucleotide translocase, Complex I, Complex II;succinate dehydrogenase, Complex III, Complex IV;cytochrome c oxidase, Complex V;ATP synthase, Inner mt-membrane transporter, Marker enzyme, Supercomplex, TCA cycle and matrix dehydrogenases, ...) of allowed values for the "Enzyme" property.
HRR: Oxygraph-2k