Diffusional effects in the steady state kinetics of ubiquinol cytochrome c reductase in bovine heart submitochondrial particles. 1988

R Fato, and C Castelluccio, and S Armaroli, and A Contarini, and G Parenti Castelli, and G Lenaz
Department of Biology, University of Bologna, Italy.

The steady-state kinetics of ubiquinol cytochrome c reductase was investigated in submitochondrial particles using ubiquinol-1 as electron donor in media of increasing viscosities obtained by water-polyethylene glycol mixtures. The minimum association rate constant, kmin = kcat/km, for cytochrome c was strongly viscosity dependent, whereas kmin for ubiquinol-1 was only weakly affected by viscosity. It is concluded that the interaction of cytochrome c with the membranous reductase is largely under diffusion control, whereas the oxidation of ubiquinol by the enzyme is not significantly controlled by diffusion in either the aqueous medium or the membrane. The results are compatible with the presence of a diffusion limited step in cytochrome c but not in ubiquinone in mitochondrial electron transfer.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D008433 Mathematics The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed) Mathematic
D008929 Mitochondria, Heart The mitochondria of the myocardium. Heart Mitochondria,Myocardial Mitochondria,Mitochondrion, Heart,Heart Mitochondrion,Mitochondria, Myocardial
D002417 Cattle Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor. Beef Cow,Bos grunniens,Bos indicus,Bos indicus Cattle,Bos taurus,Cow,Cow, Domestic,Dairy Cow,Holstein Cow,Indicine Cattle,Taurine Cattle,Taurus Cattle,Yak,Zebu,Beef Cows,Bos indicus Cattles,Cattle, Bos indicus,Cattle, Indicine,Cattle, Taurine,Cattle, Taurus,Cattles, Bos indicus,Cattles, Indicine,Cattles, Taurine,Cattles, Taurus,Cow, Beef,Cow, Dairy,Cow, Holstein,Cows,Dairy Cows,Domestic Cow,Domestic Cows,Indicine Cattles,Taurine Cattles,Taurus Cattles,Yaks,Zebus
D004058 Diffusion The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially FACILITATED DIFFUSION, is a major mechanism of BIOLOGICAL TRANSPORT. Diffusions
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D013367 Submitochondrial Particles The various filaments, granules, tubules or other inclusions within mitochondria. Particle, Submitochondrial,Particles, Submitochondrial,Submitochondrial Particle
D014450 Electron Transport Complex III A multisubunit enzyme complex that contains CYTOCHROME B GROUP; CYTOCHROME C1; and iron-sulfur centers. It catalyzes the oxidation of ubiquinol to UBIQUINONE, and transfers the electrons to CYTOCHROME C. In MITOCHONDRIA the redox reaction is coupled to the transport of PROTONS across the inner mitochondrial membrane. Complex III,Cytochrome bc1 Complex,Ubiquinol-Cytochrome-c Reductase,Coenzyme Q-Cytochrome-c Reductase,Coenzyme QH2-Cytochrome-c Reductase,Core I Protein, UCCreductase,Core I Protein, Ubiquinol-Cytochrome c Reductase,Core II Protein, UCCreductase,Core II Protein, Ubiquinol-Cytochrome c Reductase,Cytochrome b-c2 Oxidoreductase,Cytochrome bc1,Dihydroubiquinone-Cytochrome-c Reductase,QH(2)-Cytochrome-c Reductase,QH(2)-Ferricytochrome-c Oxidoreductase,Ubihydroquinone-Cytochrome-c Reductase,Ubiquinol-Cytochrome c Reductase,Ubiquinone-Cytochrome b-c2 Oxidoreductase,Coenzyme Q Cytochrome c Reductase,Coenzyme QH2 Cytochrome c Reductase,Core I Protein, Ubiquinol Cytochrome c Reductase,Core II Protein, Ubiquinol Cytochrome c Reductase,Cytochrome b c2 Oxidoreductase,Dihydroubiquinone Cytochrome c Reductase,Reductase, Ubiquinol-Cytochrome c,Ubihydroquinone Cytochrome c Reductase,Ubiquinol Cytochrome c Reductase,Ubiquinone Cytochrome b c2 Oxidoreductase

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