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Oxidation of Propionyl-CoA

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B12 revisitedOxidation of Propionyl-CoAFigure 25-20 The rearrangement catalyzed by methylmalonyl-CoA mutase.Figure 25-21 Structure of 5’-deoxyadenosyl- cobalamin (coenzyme B12).Slide 5Oxidative PhosphorylationFigure 22-12 Electron micrographs of mouse liver mitochondria. (a) In the actively respiring state. (b) In the resting state.Chemiosmotic TheorySlide 9Chemiosmotic Energy Coupling Requires MembranesSlide 11Figure 22-3 Freeze-fracture and freeze-etch electron micrographs of the inner and outer mitochondrial membranes.How could you identify and reconstruct the ETC?Coenzyme Q or UbiquinoneSlide 15Slide 16How do they fit together?Cytochrome c Absorbs Visible LightSlide 19Slide 20Iron-Sulfur CentersSlide 22Slide 23Figure 22-9 The mitochondrial electron-transport chain.Slide 25Slide 26Slide 27Slide 28Figure 22-14The mitochondrial electron-transport chain.Slide 30NADH:Ubiquinone Oxidoreductase a.k.a. Complex ISlide 32Structure of NADH:Ubiquinone OxidoreducaseNADH:Ubiquinone Oxidoreducase is a Proton PumpSuccinate Dehydrogenase a.k.a. Complex IISlide 36Slide 37Cytochrome bc1 Complex a.k.a. Complex IIISlide 39The Q CycleAnimation of Q cycleSlide 42Slide 43Cytochrome cCytochrome Oxidase a.k.a. Complex IVSlide 46Cytochrome Oxidase Passes Electrons to O2Slide 48Summary of the Electron Flow in the Respiratory ChainSlide 50Proton-motive ForceSlide 52Slide 53Slide 54Slide 55Slide 56Chemiosmotic Model for ATP SynthesisEnergy CalculatorSlide 59Slide 60Mitochondrial ATP Synthase ComplexSlide 62Figure 22-43 Model of the E. coli F1F0–ATPase.Slide 64Slide 65Slide 66Slide 67Slide 68Slide 69Slide 70Slide 71Slide 72Slide 73Slide 74Slide 75MoviesSlide 77Slide 78Slide 79Slide 80Figure 22-46 Uncoupling of oxidative phosphorylation.Figure 22-47 Mechanism of hormonally induced uncoupling of oxidative phosphorylation in brown fat mitochondria.ATP Yield From GlucoseSlide 84Let’s Sing!Slide 86Slide 87Light Energy is Converted to ATP in Plant ChloroplastsSlide 89Slide 90Various Pigments Harvest the Light EnergySlide 92Slide 93Light-Induced Redox Reactions and Electron Transfer Cause Acidification of LumenSlide 95Flow of Protons: Mitochondria, Chloroplasts, BacteriaSlide 97B12 revisitedOxidation of Propionyl-CoA•Most dietary fatty acids are even-numbered•Many plants and some marine organisms also synthesize odd-numbered fatty acids•Propionyl-CoA forms from -oxidation of odd-numbered fatty acids•Bacterial metabolism in the rumen of ruminants also produces propionyl-CoAFigure 25-20 The rearrangement catalyzed by methylmalonyl-CoA mutase.Page 923Figure 25-21Structure of 5’-deoxyadenosyl-cobalamin (coenzyme B12).Page 923Page 926Proposed mechanism of methylmalonyl-CoA mutase.Homolytic cleavageEach product gets 1 electron from the bondCobalt acts as a reversible free radical generator!Adenosyl radical abstracts H from substrateOxidative Phosphorylation•Coupling of reduction of O2 with ATP production–Substrate level phosphorylation?–High energy intermediate structure/state?–Something else?Figure 22-12 Electron micrographs of mouse liver mitochondria. (a) In the actively respiring state. (b) In the resting state.Page 806Chemiosmotic Theory•How to make an unfavorable ADP + Pi = ATP possible?•Phosphorylation of ADP is not a result of a direct reaction between ADP and some high energy phosphate carrier•Energy needed to phosphorylate ADP is provided by the flow of protons down the electrochemical gradient•The electrochemical gradient is established by transporting protons against the electrochemical gradient during the electron transportChemiosmotic Energy Coupling Requires Membranes•The proton gradient needed for ATP synthesis can be stably established across a topologically closed membrane–Plasma membrane in bacteria–Cristae membrane in mitochondria–Thylakoid membrane in chloroplasts •Membrane must contain proteins that couple the “downhill” flow of electrons in the electron transfer chain with the “uphill” flow of protons across the membrane•Membrane must contain a protein that couples the “downhill” flow of proton to the phosphorylation of ADPFigure 22-3 Freeze-fracture and freeze-etch electron micrographs of the inner and outer mitochondrial membranes.Page 799How could you identify and reconstruct the ETC?•Intact mitochondria•Submitochondrial particles•Identify components:–Pyridine-linked DH–Flavin-linked DH–Iron-sulfur proteins–Cytochromes–UbiquinoneCoenzyme Q or Ubiquinone•Ubiquinone is a lipid-soluble conjugated dicarbonyl compound that readily accepts electrons •Upon accepting two electrons, it picks up two protons to give an alcohol, ubiquinol•Ubiquinol can freely diffuse in the membrane, carrying electrons with protons from one side of the membrane to another sideHow do they fit together?•Redox potentials•Visualize redox by UV/vis•INHIBITORS!!!Cytochrome c Absorbs Visible Light•Intense Soret band near 400 nm absorbs blue light and gives cytochrome c an intense red color •Cytochromes are sometimes named by the position of their longest-wavelength peakIron-Sulfur Centers•Found in several proteins of electron transport chain, including NADH:ubiquinone oxidoreductase•Transfers one electron at a timeFigure 22-9 The mitochondrial electron-transport chain.Page 803In the presence of antimycin A and an electron donor, is Cyt b in its oxidized or reduced state?Separation of functional complexes of the respiratory chain.Figure 22-14The mitochondrial electron-transport chain.Page 808Path of electrons from NADH, succinate, fatty acyl–CoA, and glycerol 3-phosphate to ubiquinoneNADH:Ubiquinone Oxidoreductasea.k.a. Complex I•One of the largest macro-molecular assemblies in the mammalian cell•Over 40 different polypeptide chains, encoded by both nuclear and mitochondrial genes•NADH binding site in the matrix side•Non-covalently bound flavin mononucleotide (FMN) accepts two electrons from NADH•Several iron-sulfur centers pass one electron at the time toward the ubiquinone binding siteNADH:ubiquinone oxidoreductase (Complex I).Structure of NADH:Ubiquinone OxidoreducaseThe complete macromolecular assembly can be seen in electron microscopy. Part of the bacterial protein has been crystallized but the 3D structure of the membrane-spanning domain remains unknownNADH:Ubiquinone Oxidoreducase is a Proton Pump•Transfer of two electrons from NADH to uniquinone is accompanied by a transfer of protons from the matrix (N) to the


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