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General types of electron carriers
- NAD(P)H and FADH2
- Iron sulfer proteins
- Cytochromes
- Ubiquinone
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Characteristics of cytochromes
- contains heme
- different UV absorption of redox states
- different flavors
- mobile soluble e- carriers
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Characteristics of Iron-Sulfur proteins
- come in different flavors
- Fe+3 +e----->Fe+2
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Ubiquinone
- mitochondrial e- carrier
- reduced by 1 e- at a time
- ubiquinone (Oxidized)
- semiquinone (radical)
- Ubiquinol (diol)
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major complexes in electron transfer
- Complex I: NADH dehydrogenase
- Complex II: Succinate dehydrogenase
- Complex III: Oxidoreductase Dimer (Q cycle)
- Cytochrome C: mobile, soluble e- carrier
- Complex IV: Cytochrome oxidase
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products of each complex
- Complex I: 4H+ Pumped to P side, 1 QH2
- Complex II: 1 QH2
- Complex III: 2 cyt red, 1 Q, 4H+
- Comoplex IV: 4 cyt ox, 2 H2O, 4 H+
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Big picture equation for the number of protons transferred per NADH
NADH + 11H +0.5O2 -----> NAD+ + 10H + H2O
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How order of electron carriers were determined
- detection of ox,red forms using visible and epr spectrum
- order by E?
- Kinetics of oxidation
- effects of specific inhibitors
- biochemical dissection of complexes
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Chemisomotic hypothesis
- electron transfer causes H+ flux
- destruction of H+ gradient blocks ATP synthesis
- Artificially induced H+ gradient drives ATP synthesis w/o electron transfer
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experimental test for C predictions
- 1. Flux is created when O2 is added to airtight mito media
- 2. add H+ to matrix=no gradient
- 3. create artificial gradient with lowered pH and remove cation from matrix
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Role of Fo in ATP synthase
Integral membrane, H+ is pumped through it and it causes the other part to rotate
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role F1 in ATP Synthase
converts ADP to ATP
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shuttles that transport electrons into the matrix
- Malate-Aspartate Shuttle- to complex I yields 5 ATP
- Glycerol-3-Phosphate Shuttle- bypass complex I using QH2 yields 3 atp
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reactive oxygen species
- superoxide O2-
- peroxide H2O2
- hydroxyl free radical .OH
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formation of superoxide
O2 + e- ----> O2-
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formation of peroxide
O2 + 2e- ---> H2O2
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formation of hydroxyl free radical
O2 + 3e- + 3H+ -----> H2O + .OH
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how does the body get rid of superoxides
- superoxide dismutase
- turns to peroxide and O2
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How does the body get rid of peroxide
- peroxidase, catalase
- turns it to H2O and water
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