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Citric Acid Cycle Generates Reductive Equivalents Utilized in Respiration

Citric Acid Cycle Generates Reductive Equivalents Utilized in Respiration. Citric Acid Cycle: A Two Stage Process. Stage One : C 4 + C 2 condensation C 6 tricarboxylic acid Oxidative decarboxylation 2 CO 2 Succinyl CoA Net Result: 2NADH + 2CO 2 + Succinyl CoA.

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Citric Acid Cycle Generates Reductive Equivalents Utilized in Respiration

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  1. Citric Acid Cycle Generates Reductive Equivalents Utilized in Respiration

  2. Citric Acid Cycle: A Two Stage Process Stage One: C4 + C2 condensation C6tricarboxylic acid Oxidative decarboxylation 2 CO2SuccinylCoA Net Result: 2NADH + 2CO2 + SuccinylCoA

  3. C4 + C2 Condensation Reaction Condensation catalyzed by enzyme dimer Citrate Synthase RxN Driver

  4. Citrate Synthase Reaction

  5. Citrate Synthase Reaction

  6. Citrate Synthase Reaction

  7. Citrate Synthase Reaction

  8. Citrate to Isocitrate Conversion via Aconitase Hydroxyl shift for subsequent oxidative decarboxylation

  9. IsocitrateDehydrogenase: Oxidation and Decarboxylation Oxalosuccinate not released from the enzyme

  10. α-KetoglutarateDehydrogenase: Oxidation and Decarboxylation How similar is α-ketoglutaratedehydrogenase with pyruvatedehydrogenase in terms of substrate components? Reaction mechanism?

  11. Citric Acid Cycle Part Two: Oxaloacetate Regeneration Succinyl Coenzyme A Synthetase couples hydrolysis of Coenzyme A (-33 kJ/mol) with GTP formation (-30 kJ/mol) The energetics works but what about the reaction mechanism?

  12. SuccinylCoA-Sythetase Generates GTP What is the Nu:-, E, and leaving group with GTP generation?

  13. Oxaloacetate Enzyme Regeneration from Succinate • SuccinateDehydrogenase • Fumerase • MalateDehydrogenase

  14. A Color-Coded Citric Acid Cycle Isocitrate is prochiral Succinate is a symmetric molecule Generated products include: 2CO2 + 3NADH + 1FADH2 + GTP + CoA

  15. Citric Acid Energetics

  16. Citric Acid Cycle Regulation Points ATP and NADH are indicators of a high energy state ADP an indicator of a low energy state Regulatory sites include: Isocitratedehydrogenase α-Ketoglutaratedehydrogenase Pyruvatedehydrogenase

  17. Citric Acid Cycle is a Source for Biosynthetic Precursors

  18. TransaminationReaction

  19. Citric Acid Cycle Intermediates: Replenished as Metabolites are Drawn Off for Biosynthesis Anapleurotic reactions lead to a replenishment of pathway components (e.g.pyruvatecarboxylase).

  20. Problems: 1, 3, 5, 7 and 9

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