Bianchi 2004 J Biol Chem: Difference between revisions
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|discipline=Mitochondrial Physiology, Biomedicine | |discipline=Mitochondrial Physiology, Biomedicine | ||
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Revision as of 10:34, 27 February 2013
Bianchi C, Genova ML, Parenti Castelli G, Lenaz G (2004) The mitochondrial respiratory chain is partially organized in a supercomplex assembly: kinetic evidence using flux control analysis. J Biol Chem 279: 36562-36569. |
Bianchi C, Genova ML, Parenti Castelli G, Lenaz G (2004) J Biol Chem
Abstract: The model of the respiratory chain in which the enzyme complexes are independently embedded in the lipid bilayer of the inner mitochondrial membrane and connected by randomly diffusing coenzyme Q and cytochrome c is mostly favored. However, multicomplex units can be isolated from mammalian mitochondria, suggesting a model based on direct electron channeling between complexes. Kinetic testing using metabolic flux control analysis can discriminate between the two models: the former model implies that each enzyme may be rate-controlling to a different extent, whereas in the latter, the whole metabolic pathway would behave as a single supercomplex and inhibition of any one of its components would elicit the same flux control. In particular, in the absence of other components of the oxidative phosphorylation apparatus (i.e. ATP synthase, membrane potential, carriers), the existence of a supercomplex would elicit a flux control coefficient near unity for each respiratory complex, and the sum of all coefficients would be well above unity. Using bovine heart mitochondria and submitochondrial particles devoid of substrate permeability barriers, we investigated the flux control coefficients of the complexes involved in aerobic NADH oxidation (I, III, IV) and in succinate oxidation (II, III, IV). Both Complexes I and III were found to be highly rate-controlling over NADH oxidation, a strong kinetic evidence suggesting the existence of functionally relevant association between the two complexes, whereas Complex IV appears randomly distributed. Moreover, we show that Complex II is fully rate-limiting for succinate oxidation, clearly indicating the absence of substrate channeling toward Complexes III and IV. โข Keywords: Supercomplex
Labels:
Organism: Mammals"Mammals" is not in the list (Human, Pig, Mouse, Rat, Guinea pig, Bovines, Horse, Dog, Rabbit, Cat, ...) of allowed values for the "Mammal and model" property.
Tissue;cell: Heart
Preparation: Isolated Mitochondria"Isolated Mitochondria" is not in the list (Intact organism, Intact organ, Permeabilized cells, Permeabilized tissue, Homogenate, Isolated mitochondria, SMP, Chloroplasts, Enzyme, Oxidase;biochemical oxidation, ...) of allowed values for the "Preparation" property., SMP
HRR: Oxygraph-2k
bovine