1. Chapter 10
The Citrate Cycle

2. 10.1 The Citrate Cycle Captures Energy Using Redox Reactions
Copyright © 2017 W. W. Norton & Company

3. Overview of the Citrate Cycle
Copyright © 2017 W. W. Norton & Company

4. The Metabolic “Engine”
Copyright © 2017 W. W. Norton & Company

5. 10.2 Pyruvate Dehydrogenase Converts Pyruvate to Acetyl-CoA
Copyright © 2017 W. W. Norton & Company

6. NAD+ and FAD Redox Reactions
Common enzymes in oxidation–reduction reactions
Copyright © 2017 W. W. Norton & Company

7. Copyright © 2017 W. W. Norton & Company
Coenzyme A (CoA)
Copyright © 2017 W. W. Norton & Company

8. Thiamine Pyrophosphate (TPP)
Copyright © 2017 W. W. Norton & Company

9. Copyright © 2017 W. W. Norton & Company
α-lipoic Acid
Copyright © 2017 W. W. Norton & Company

10. Pyruvate Dehydrogenase
Copyright © 2017 W. W. Norton & Company

11. Arsenic Inhibits Pyruvate Dehydrogenase
Copyright © 2017 W. W. Norton & Company

12. 10.3 Enzymatic Reactions of the Citrate Cycle
Enzyme
Standard free energy changes (kJ/mol)
1. acetyl-CoA plus Oxaloacetate plus upper H 2 upper O yields upper C-o upper A plus Citrate
Citrate synthase
Negative 31.4
2. Citrate is in equilibrium with Isocitrate
Aconitase
Plus 6.7
3. Isocitrate plus positive upper N upper A upper D ion yields alpha-Ketoglutarate plus upper N upper A upper D upper H plus upper C upper O 2 plus positive upper H ion.
Isocitrate dehydrogenase
Negative 20.9
4. alpha-Ketoglutarate plus upper C-o upper A plus positive upper N upper A upper D ion yields Succinyl-CoA plus upper N upper A upper D upper H plus upper C upper O 2 plus positive upper H ion.
Alpha-Ketoglutarate dehydrogenase
Negative 33.5
5. Succinyl-CoA plus GDP plus upper P-i is in equilibrium with Succinate plus GTP plus upper C-a upper A
Succinyl-CoA synthase
Negative 2.9
6. Succinate plus upper F upper A uppe D is in equilibrium with Fumarate plus upper F upper A upper D upper H 2.
Succinate dehydrogenase
Plus 0.4
7. Fumarate plus upper H 2 upper O is in equilibrium with Malate
Fumarase
Negative 3.8
8. Malate plus positive upper N upper A upper D ion is in equilibrium with Oxaloacetate plus upper N upper A upper D upper H plus positive upper H ion.
Malate dehydrogenase
Plus 29.3
Copyright © 2017 W. W. Norton & Company

13. Copyright © 2017 W. W. Norton & Company
The Citrate Cycle
Figure The eight enzymatic reactions in the citrate cycle.
Copyright © 2017 W. W. Norton & Company

14. The Citrate Cycle Animation
Click to view the Citrate Cycle animation
Copyright © 2017 W. W. Norton & Company

15. The Citrate Cycle (Step-by-Step)
Copyright © 2017 W. W. Norton & Company

16. Copyright © 2017 W. W. Norton & Company
Aconitase
Copyright © 2017 W. W. Norton & Company

17. Isocitrate Dehydrogenase
Copyright © 2017 W. W. Norton & Company

18. α-Ketoglutarate Dehydrogenase
Copyright © 2017 W. W. Norton & Company

19. Succinyl-CoA Synthetase
Copyright © 2017 W. W. Norton & Company

20. Succinate Dehydrogenase
Copyright © 2017 W. W. Norton & Company

21. Copyright © 2017 W. W. Norton & Company
Fumarase
Copyright © 2017 W. W. Norton & Company

22. Copyright © 2017 W. W. Norton & Company
Malate Dehydrogenase
Copyright © 2017 W. W. Norton & Company

23. 10.4 Regulation of the Citrate Cycle
Copyright © 2017 W. W. Norton & Company

24. Control Points of the Citrate Cycle
Copyright © 2017 W. W. Norton & Company

25. Feedback Inhibition in the Citrate Cycle
Copyright © 2017 W. W. Norton & Company