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Citrate Cycle (CC) - exercise -

Citrate Cycle (CC) - exercise -. Vladimíra Kvasnicová. Citrate cycle is also called. citric acid cycle tricarboxylic acid cycle Krebs cycle electron transport chain. Citrate cycle is also called. citric acid cycle tricarboxylic acid cycle Krebs cycle electron transport chain.

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Citrate Cycle (CC) - exercise -

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  1. Citrate Cycle (CC)- exercise - Vladimíra Kvasnicová

  2. Citrate cycle is also called • citric acid cycle • tricarboxylic acid cycle • Krebs cycle • electron transport chain

  3. Citrate cycle is also called • citric acid cycle • tricarboxylic acid cycle • Krebs cycle • electron transport chain

  4. The figure is adopted from the book: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2

  5. simplification: The figure is found at http://www.sp.uconn.edu/~bi107vc/images/mol/krebs_cycle.gif (December 2006)

  6. citric acid (2-hydroxypropane-1,2,3-tricarboxylicacid)

  7. Hans Adolf Krebs The Nobel Prize in Physiology or Medicine in 1953 for his discovery of the citric acid cycle.

  8. = the other metabolic pathway The figure is adopted from the book: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2

  9. Citrate cycle • is a catabolic pathway • participates in anabolic reactions • belongs among oxidative processes • produces carbon dioxide

  10. Citrate cycle • is a catabolic pathway • participates in anabolic reactions • belongs among oxidative processes • produces carbon dioxide

  11. The figure is found at http://www.holon.se/folke/kurs/Distans/Ekofys/Recirk/Eng/regcyc5.jpg (December 2006)

  12. Amphibolic nature of thecitrate cycle The figure is found athttp://www.tcd.ie/Biochemistry/IUBMB-Nicholson/gif/13.html

  13. Enzymes of the citrate cycle • are found in all cells • are located in a mitochondrion • catalyze freely reverzible reactions • produce coenzymes which are regenerated in a respiratory chain

  14. Enzymes of the citrate cycle • are found in all cells • are located in a mitochondrion • catalyze freely reverzible reactions • produce coenzymes which are regenerated in a respiratory chain

  15. strongly exergonic reactions The figure is found at http://www.metabolic-database.com/html/body_glutaminolysis__zeichnung3.html (December 2006)

  16. The substances enter the CC • acetyl~CoA • NAD+ and FAD • carbon skeleton of amino acids • GDP

  17. The substances enter the CC • acetyl~CoA (→ 2 CO2) • NAD+ and FAD (→ NADH+H+ + FADH2) • carbon skeleton of amino acids • GDP (→ GTP)

  18. The figure is found at http://www.elmhurst.edu/~chm/vchembook/images/590metabolism.gif (December 2006)

  19. Choose products of the cycle • pyruvate • acetyl-CoA • NADH • FADH2

  20. Choose products of the cycle • pyruvate • acetyl-CoA • NADH(→ electron transport chain) • FADH2(→ electron transport chain)

  21. Products of the citrate cycle The figure is found at http://www.hupe.hu/szerv/tanszekek/kio/im/oktat/SEJTBIO/citratkor/citr_summa_e.html (December 2006)

  22. Energy released from oxidation of acetyl group in the CC is conserved in • GTP • ATP • NADH • FADH2

  23. Energy released from oxidation of acetyl group in the CC is conserved in • GTP(succinyl~Co → succinate) • ATP (GTP + ADP → GDP + ATP) • NADH (3x) • FADH2 (1x)

  24. The figure is found at http://lecturer.ukdw.ac.id/dhira/Metabolism/Respiration.html (December 2006)

  25. NAD+ is reduced to NADH+H+ in the reactions of the CC • isocitrate → -ketoglutarate • -ketoglutarate → succinyl~CoA • succinate → fumarate • malate → oxaloacetate

  26. NAD+ is reduced to NADH+H+ in the reactions of the CC • isocitrate → -ketoglutarate • -ketoglutarate → succinyl~CoA • succinate → fumarate • malate → oxaloacetate

  27. „F“ →Fumarateand FADH2 The figure is found at http://lecturer.ukdw.ac.id/dhira/Metabolism/Respiration.html (December 2006)

  28. Carbon dioxide (CO2) is produced in the reactions of the CC • oxaloacetate + acetyl~CoA → citrate • citrate → isocitrate • isocitrate → -ketoglutarate • -ketoglutarate → succinyl~CoA

  29. Carbon dioxide (CO2) is produced in the reactions of the CC • oxaloacetate(C4) + acetyl~CoA(C2) → citrate(C6) • citrate (C6)→ isocitrate (C6) • isocitrate (C6)→ -ketoglutarate(C5) • -ketoglutarate(C5)→ succinyl~CoA(C4) ! count number of carbons !

  30. The figure is found at http://lecturer.ukdw.ac.id/dhira/Metabolism/Respiration.html (December 2006)

  31. Choose reactions that lead tonet synthesis of CC intermediates(= anaplerotic reactions) • pyruvate → acetyl~CoA (PDH) • pyruvate → oxaloacetate (pyruvate carboxylase) • aspartate → oxaloacetate (AST) • glutamate → -ketoglutarate (ALT)

  32. Choose reactions that lead tonet synthesis of CC intermediates(= anaplerotic reactions) • pyruvate → acetyl~CoA(PDH) • pyruvate → oxaloacetate(pyruvate carboxylase) • aspartate → oxaloacetate(AST) – the reaction consumes 2-oxoglutarate (+1 -1 = 0 net synthesis) • glutamate → -ketoglutarate(ALT)

  33. The figure is found at http://web.indstate.edu/thcme/mwking/tca-cycle.html (prosinec 2006)

  34. The most important anaplerotic reaction: pyruvate carboxylase The figure is found at http://www.bmb.leeds.ac.uk/illingworth/metabol/2120lec3.htm#krebs (December 2006)

  35. The substances can be synthesized from intermediates of the CC • amino acids • heme • glucose • fatty acids

  36. The substances can be synthesized from intermediates of the CC • amino acids • heme • glucose • fatty acids

  37. Citrate cycleas a source of substrates used in a synthesis of other molecules The figure is found athttp://www.tcd.ie/Biochemistry/IUBMB-Nicholson/gif/13.html

  38. The enzymes regulate velocity of the CC • citrate synthase • isocitrate dehydrogenase • -ketoglutarate dehydrogenase • hexokinase

  39. The enzymes regulate velocity of the CC • citrate synthase • isocitrate dehydrogenase • -ketoglutarate dehydrogenase • hexokinase

  40. The citrate cycle is inhibited by •  ATP/ADP •  NADH,  NAD+ •  NADH/NAD+ •  AMP

  41. The citrate cycle is inhibited by •  ATP/ADP •  NADH,  NAD+ •  NADH/NAD+ •  AMP

  42. Regulation of the citrate cycle = by availability of substrates and consumption of produts

  43. Citrate • is formed from oxaloacetate and acetic acid • is transported to the cytoplasm if accumulates • acts as an inhibitor of glycolysis • activates synthesis of fatty acids

  44. Citrate • is formed from oxaloacetate and acetic acid • is transported to the cytoplasm if accumulates • acts as an inhibitor of glycolysis • activates synthesis of fatty acids energy excess → it is stored in a glycogen and fat

  45. ATP The figure is found at http://www.metabolic-database.com/html/body_glutaminolysis__zeichnung3.html (December 2006)

  46. see next presentation The figure is adopted from the book: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2

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