Distribution of control of oxidative phosphorylation in mitochondria oxidizing NAD-linked substrates.
The flux control distribution of the net rate of state 3 respiration was determined in heart and kidney mitochondria incubated with low concentrations of pyruvate (0.5 mM) or 2-oxoglutarate (1 mM), and in conditions that led to activation of NAD-linked dehydrogenases, i.e., high substrate or Ca2+ concentrations. Control of flux was exerted by the ATP/ADP carrier (flux control coefficient, ci = 0.37) and Site 1 of the respiratory chain (ci = 0.28) when dehydrogenase activity was low. Control of the process shifted to the ATP synthase (ci = 0.32) and the Pi carrier (Ci = 0.27) when dehydrogenases were activated by high pyruvate and high Ca2+. The changes in the control exerted by the ATP/ADP carrier and the ATP synthase were not due to changes in the transmembrane potential, nor to a modification of intramitochondrial ATP/ADP ratios. Applying the summation theorem of the control analysis, it was found that at low Ca2+ and pyruvate concentrations the dehydrogenases shared the control of state 3 respiration with other steps. The NAD-linked dehydrogenases did not exert any significant control at high Ca2+ or high pyruvate concentrations.
Moreno-Sánchez
R
R
Departamento de Bioquímica, Instituto Nacional de Cardiología, México, D.F.
Devars
S
S
López-Gómez
F
F
Uribe
A
A
Corona
N
N
D000818:Animals; D007668:Kidney / Q000378:metabolism; D007700:Kinetics; D008564:Membrane Potentials; D008929:Mitochondria, Heart / Q000378:metabolism*; D009243:NAD / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D010088:Oxidoreductases / Q000378:metabolism; D010619:Phenazines / Q000378:metabolism; D011773:Pyruvates / Q000378:metabolism; D019289:Pyruvic Acid; D051381:Rats; D011919:Rats, Inbred Strains; D013379:Substrate Specificity
D010619:Phenazines; D011773:Pyruvates; D009243:NAD; D019289:Pyruvic Acid; D010088:Oxidoreductases; C009195:safranine T