Dalmonte 2009 J Biol Chem
Dalmonte ME, Forte E, Genova ML, Giuffrè A, Sarti P, Lenaz G (2009) Control of respiration by cytochrome c oxidase in intact cells: role of the membrane potential. J Biol Chem 284:32331-5. |
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 (ΞΟ) and chemical (ΞpH) component of the mitochondrial transmembrane proton electrochemical gradient (ΞΞΌH+) was investigated. The overall O2 consumption and specific CcOX activity of actively phosphorylating cells were titrated with cyanide under conditions in which ΞΟ and ΞpH 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 ΞΟ is maximal, and in the presence of nigericin and valinomycin (CIV = 0.77), when ΞΞΌH+ is abolished. In contrast, CcOX displayed a markedly lower control coefficient (CIV = 0.30) upon addition of valinomycin, when ΞΟ is converted into ΞpH. These results show that ΞΟ is responsible for the tight control of CcOX over respiration in actively phosphorylating cells. β’ Keywords: Nigericin, Valinomycin, Cytochrome C oxidase, Membrane potential
β’ O2k-Network Lab: IT Rome Sarti P, IT Bologna Lenaz G, IT Bologna Genova ML
Labels:
Organism: Human, Rat
Tissue;cell: Liver
Preparation: Intact cells
Enzyme: Complex IV;cytochrome c oxidase
HRR: Oxygraph-2k