electron transport chain lecture notes for medical students, bds as well as nursing students

1. Department of Biochemistry, NGMC, Chisapani, Nepal
Thursday,
September 15,
2016
Rajesh Chaudhary
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http://www.slideshare.net/RajeshChaudhary10
Note / Remember

2. Biomedical importance
Oxidative phosphorylation (OXPHOS) is essential for
generation of high energy intermediate – ATP.
Inhibition of OXPHOS results into fatal consequences –
myopathy, encephalopathy and lactic acidosis.
Drugs and poisons that inhibits OXPHOS: amobarbital,
cyanide, carbon monoxide.
Thursday,
September 15,
2016
Rajesh Chaudhary
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3. The system in mitochondria that couples respiration to
generation of high energy intermediate, ATP, is termed as
Oxidative Phosphorylation (OXPHOS).
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September 15,
2016
Rajesh Chaudhary
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— Harper’s Biochemistry, 25th. Edition

4. Respiratory chain collects & oxidizes
reducing equivalents
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September 15,
2016
Rajesh Chaudhary
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5. Phases of metabolism
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September 15,
2016
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Phases
metabolism
1. Primary
2. Secondary /
Intermediate
3. Tertiary

6. Electron transfer reaction in
mitochondria
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7. Mitochondria and Oxidative
phosphorylation
 The transfer of electron is done by the set of protein
complexes.
Thursday,
September 15,
2016
Rajesh Chaudhary
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Outer mitochondrial membrane

8. Mitochondrial matrix
 The mitochondrial matrix enclosed by the inner membrane,
contains the pyruvate dehydrogenase complex and the
enzymes of the citric acid cycle, the fatty acid b-oxidation
pathway, and the pathways of amino acid oxidation – all
the pathways of fuel oxidation except glycolysis, which takes
place in cytosol.
Thursday,
September 15,
2016
Rajesh Chaudhary
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— Lehninger’s Principle of Biochemistry, 5th. Edition

9. Mitochondria and Oxidative
phosphorylation
 Mitochondria is the site of oxidative phosphorylation.
 Oxidative phosphorylation (OXPHOS): metabolic pathways in
which cells use enzymes to oxidize nutrients thereby releasing
energy which is used to reform ATP.
 Takes place inside mitochondria.
 During OXPHOS, electrons are transferred from donor to acceptor.
Thursday,
September 15,
2016
Rajesh Chaudhary
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10. Electrons are funneled to universal electron
acceptor
 Oxidative phosphorylation beings with the entry of electrons
into the respiratory chain.
 Most of these electrons arise from the action of
dehydrogenases that collect electrons from catabolic
pathways and funnel them into universal electron
acceptors – nicotinamide nucleotide (NAD+ or NADP+) of
Flavin nucleotides (FMN or FAD).
Thursday,
September 15,
2016
Rajesh Chaudhary
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11. Malate-Aspartate shuttle
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September 15,
2016
Rajesh Chaudhary
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12. Requirements for ATP generation from
OXPHOS
 1. An electron donor: NADH and/or FAD(2H)
 2. An electron acceptor: O2
 3. Intact inner mitochondrial membrane that is impermeable to
protons.
 4. All components of electron transport chain.
 5. ATP synthase
Thursday,
September 15,
2016
Rajesh Chaudhary
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Oxidative phosphorylation is regulated by the rate of ATP utilization !

13. 1. Complex I / NADH
dehydrogenase
2. Complex II / Succinate
dehydrogenase
3. Complex III / Cytochrome b-C1
4. Complex IV / Cytochrome C
oxidase
5. Complex V / ATP synthase
Components of Electron Transport
Chain (ETC)
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September 15,
2016
Rajesh Chaudhary
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Components of ETC

14. Major components of ETC
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September 15,
2016
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Complex III
ETC also contains:
1. Coenzyme Q
2. Cytochrome C

15. With the exception of Coenzyme Q
(CoQ) rest are proteins in ETC !
Thursday,
September 15,
2016
Rajesh Chaudhary
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16. Electron Transport Chain (ETC)
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September 15,
2016
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17. Chemiosmotic model of ATP generation
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September 15,
2016
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18. Components of ETC
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September 15,
2016
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19. Coenzyme Q
 The only component of ETC that is not protein bound.
 Large hydrophobic side chain of 10 isoprenoid units (50
carbons) confers lipid solubility.
 It is also called Ubiquinone.
Thursday,
September 15,
2016
Rajesh Chaudhary
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20. Adenosine Triphosphate Synthase
(ATP synthase)
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September 15,
2016
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Also known as
F0F1 ATPase
Stalk

21. Binding-change mechanism for ATP
synthesis
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September 15,
2016
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Link for the video down below: https://www.youtube.com/watch?v=3y1dO4nNaKY

22. Electrons pass through series of membrane-
bound carriers
 Usually carrier molecules are integral proteins with prosthetic
group capable of accepting and donating one or two
electrons.
 Types of electron transfer in OXPHOS
1. Direct transfer of electrons, as in the reduction of Fe3+ to Fe2+.
2. Transfer as a hydrogen atom (H+ + e-).
3. Transfer as hydride ion which bears two electrons (:H-).
Thursday,
September 15,
2016
Rajesh Chaudhary
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23. Summary of flow of electrons and protons
through four complexes of the respiratory
chain
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September 15,
2016
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24. Proposed sites of inhibition
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September 15,
2016
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25. References
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September 15,
2016
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