BCH 5045 Graduate Survey of Biochemistryhort.ifas.ufl.edu/faculty/guy/bch5045/Lecture Files/Lecture...
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Images from the Text are protected by Copyright (c) 2008 by W. H. Freeman and Company, and by the licensors of W. H. Freeman and Company. Living Graphs software (c) 2008 Sumanas, Inc. ALL RIGHTS RESERVED. Commentary by the instructor is protected by Copyright (c) 2011. ALL RIGHTS RESERVED. BCH 5045 Graduate Survey of Biochemistry Instructor: Charles Guy Producer: Ron Thomas Director: Glen Graham Lecture 52 Slide sets available at: http://hort.ifas.ufl.edu/teach/guyweb/bch5045/index.html
BCH 5045 Graduate Survey of Biochemistryhort.ifas.ufl.edu/faculty/guy/bch5045/Lecture Files/Lecture 52.pdf · Graduate Survey of Biochemistry . Instructor: Charles Guy . Producer:
Images from the Text are protected by Copyright (c) 2008 by W. H. Freeman and Company, and by the licensors of W. H. Freeman and Company. Living Graphs software (c) 2008 Sumanas, Inc. ALL RIGHTS RESERVED.
Commentary by the instructor is protected by Copyright (c) 2011. ALL RIGHTS RESERVED.
BCH 5045
Graduate Survey of Biochemistry
Instructor: Charles Guy Producer: Ron Thomas Director: Glen Graham
Lecture 52
Slide sets available at: http://hort.ifas.ufl.edu/teach/guyweb/bch5045/index.html
Images from the Text are protected by Copyright (c) 2008 by W. H. Freeman and Company, and by the licensors of W. H. Freeman and Company. Living Graphs software (c) 2008 Sumanas, Inc. ALL RIGHTS RESERVED.
Commentary by the instructor is protected by Copyright (c) 2011. ALL RIGHTS RESERVED.
Images from the Text are protected by Copyright (c) 2008 by W. H. Freeman and Company, and by the licensors of W. H. Freeman and Company. Living Graphs software (c) 2008 Sumanas, Inc. ALL RIGHTS RESERVED.
Commentary by the instructor is protected by Copyright (c) 2011. ALL RIGHTS RESERVED.
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FIGURE 19-19 Chemiosmotic model. In this simple representation of the chemiosmotic theory applied to mitochondria, electrons from NADH and other oxidizable substrates pass through a chain of carriers arranged asymmetrically in the inner membrane. Electron flow is accompanied by proton transfer across the membrane, producing both a chemical gradient (ΔpH) and an electrical gradient (Δψ). The inner mitochondrial membrane is impermeable to protons; protons can reenter the matrix only through proton-specific channels (Fo). The proton-motive force that drives protons back into the matrix provides the energy for ATP synthesis, catalyzed by the F1 complex associated with Fo.
Images from the Text are protected by Copyright (c) 2008 by W. H. Freeman and Company, and by the licensors of W. H. Freeman and Company. Living Graphs software (c) 2008 Sumanas, Inc. ALL RIGHTS RESERVED.
Commentary by the instructor is protected by Copyright (c) 2011. ALL RIGHTS RESERVED.
Mohammed Sabar, Janneke Balk and Christopher J. Leaver. The Plant Journal Volume 44, 893-901
Figure 1. (a) Mitochondrial respiratory complexes from Arabidopsis cell culture resolved by Blue Native-PAGE and stained with Serva Blue G. (b) Density measurement of the Serva Blue staining of complexes I, II, III, IV and V. Blue native-PAGE is an approach that is gentle enough that large complexes remain intact during extraction and electrophoresis.
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FIGURE 19-19 Chemiosmotic model. In this simple representation of the chemiosmotic theory applied to mitochondria, electrons from NADH and other oxidizable substrates pass through a chain of carriers arranged asymmetrically in the inner membrane. Electron flow is accompanied by proton transfer across the membrane, producing both a chemical gradient (ΔpH) and an electrical gradient (Δψ). The inner mitochondrial membrane is impermeable to protons; protons can reenter the matrix only through proton-specific channels (Fo). The proton-motive force that drives protons back into the matrix provides the energy for ATP synthesis, catalyzed by the F1 complex associated with Fo.
Images from the Text are protected by Copyright (c) 2008 by W. H. Freeman and Company, and by the licensors of W. H. Freeman and Company. Living Graphs software (c) 2008 Sumanas, Inc. ALL RIGHTS RESERVED.
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FIGURE 19-17 Proton-motive force. The inner mitochondrial membrane separates two compartments of different [H+], resulting in differences in chemical concentration (ΔpH) and charge distribution (Δψ) across the membrane. The net effect is the proton-motive force (ΔG), which can be calculated as shown here. This is explained more fully in the text.
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ROS can form in mitochondria when the rate of electron entry into the respiratory chain and the rate of electron transfer through the chain to the terminal electron acceptor oxygen is mismatched creating the superoxide radical (･O2–) between complexes I and III as a partially reduced ubiquinone radical (･O–) donates an electron to O2 instead of complex III.
Glutathione plays a very important role in eliminating the ROS before serious damage to the organelle is done.
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FIGURE 19-18 ROS formation in mitochondria and mitochondrial defenses. When the rate of electron entry into the respiratory chain and the rate of electron transfer through the chain are mismatched, superoxide radical (･O2–) production increases at Complexes I and III as the partially reduced ubiquinone radical (･O–) donates an electron to O2. Superoxide acts on aconitase, a 4Fe-4S protein, to release Fe2+. In the presence of Fe2+, the Fenton reaction leads to formation of the highly reactive hydroxyl free radical (･OH). The reactions shown in blue defend the cell against the damaging effects of superoxide. Reduced glutathione (GSH; see Figure 22-27) donates electrons for the reduction of H2O2 and of the oxidized Cys residues (—S—S—) of enzymes and other proteins, and GSH is regenerated from the oxidized form (GSSG) by reduction with NADPH.
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TABLE 19-4 Agents That Interfere with Oxidative Phosphorylation or Photophosphorylation
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FIGURE 19-6 Method for determining the sequence of electron carriers. This method measures the effects of inhibitors of electron transfer on the oxidation state of each carrier. In the presence of an electron donor and O2, each inhibitor causes a characteristic pattern of oxidized/ reduced carriers: those before the block become reduced (blue), and those after the block become oxidized (pink).
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Sometimes ATP is not the need, but another functionally different purpose is provided by the electron transport chain. One purpose is to make heat to warm floral parts to volatilize aromatic insect attractants to bring insects to the flower to carry out pollination as in the case of the skunk cabbage shown on the left.
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BOX 19-1 FIGURE 2 Electron carriers of the inner membrane of plant mitochondria. Electrons can flow through Complexes I, III, and IV, as in animal mitochondria, or through plant-specific alternative carriers by the paths shown with blue arrows. BOX 19-1 FIGURE 1 Eastern skunk cabbage
Images from the Text are protected by Copyright (c) 2008 by W. H. Freeman and Company, and by the licensors of W. H. Freeman and Company. Living Graphs software (c) 2008 Sumanas, Inc. ALL RIGHTS RESERVED.
Commentary by the instructor is protected by Copyright (c) 2011. ALL RIGHTS RESERVED.
Presenter
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FIGURE 19-19 Chemiosmotic model. In this simple representation of the chemiosmotic theory applied to mitochondria, electrons from NADH and other oxidizable substrates pass through a chain of carriers arranged asymmetrically in the inner membrane. Electron flow is accompanied by proton transfer across the membrane, producing both a chemical gradient (ΔpH) and an electrical gradient (Δψ). The inner mitochondrial membrane is impermeable to protons; protons can reenter the matrix only through proton-specific channels (Fo). The proton-motive force that drives protons back into the matrix provides the energy for ATP synthesis, catalyzed by the F1 complex associated with Fo.
Images from the Text are protected by Copyright (c) 2008 by W. H. Freeman and Company, and by the licensors of W. H. Freeman and Company. Living Graphs software (c) 2008 Sumanas, Inc. ALL RIGHTS RESERVED.
Commentary by the instructor is protected by Copyright (c) 2011. ALL RIGHTS RESERVED.
Presenter
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FIGURE 19-20a Coupling of electron transfer and ATP synthesis in mitochondria. In experiments to demonstrate coupling, mitochondria are suspended in a buffered medium and an O2 electrode monitors O2 consumption. At intervals, samples are removed and assayed for the presence of ATP. (a) Addition of ADP and Pi alone results in little or no increase in either respiration (O2 consumption; black) or ATP synthesis (red). When succinate is added, respiration begins immediately and ATP is synthesized. Addition of cyanide (CN–), which blocks electron transfer between cytochrome oxidase (Complex IV) and O2, inhibits both respiration and ATP synthesis. FIGURE 19-20b Coupling of electron transfer and ATP synthesis in mitochondria. In experiments to demonstrate coupling, mitochondria are suspended in a buffered medium and an O2 electrode monitors O2 consumption. At intervals, samples are removed and assayed for the presence of ATP. (b) Mitochondria provided with succinate respire and synthesize ATP only when ADP and Pi are added. Subsequent addition of venturicidin or oligomycin, inhibitors of ATP synthase, blocks both ATP synthesis and respiration. Dinitrophenol (DNP) is an uncoupler, allowing respiration to continue without ATP synthesis.
