Tricarboxylic acid cycle (krebs cycle)

Tricarboxylic Acid Cycle by Sir Yhong Alderite.

1. {{
TRICARBOXYLIC TRICARBOXYLIC
ACID CYCLEACID CYCLE
Yhong Alderite ,MSERMYhong Alderite ,MSERM

2. STEP 1: CITRATE SYNTHASE
Process:
1. Formation of citric acid
2. Dehydration
Enzyme: citrate synthase

3. Step 2: Aconitase Reaction
Process : Hydration
Enzyme: Aconitase

4. Step 3: Isocitrate Dehydrogenase Rxn
Process:
•Dehydrogenation I
•Decarboxylation
Enzyme: isocitrate dehydrogenase

5. Step 4: a-Ketoglutarate Dehydrogenase Rxn
Process: Oxidative decarboxylation
Enzyme: a-ketoglutarate dehydrogenase

6. Step 5: Succinyl Co A Synthetase Rxn
Process:Oxidative decarboxylation
Enzyme: Succinyl-CoA synthetase

7. Step 6 : Succinate Dehydrogenase Rxn
Process: Oxidation
Enzyme: succinate dehydrogenase

8. Step 7: Fumarase Rxn
Process: Hydration
Enzyme: Fumarase

9. Step 8: Malate Dehydrogenase Rxn
Process: Dehydrogenation
Enzyme: malate dehydrogenase

10. Three control points within the cycleThree control points within the cycle
– – citrate synthase, isocitrate dehydrogenase, and a -ketoglutarate citrate synthase, isocitrate dehydrogenase, and a -ketoglutarate
dehydrogenase, are the rate limiting and regulatory enzymes of the dehydrogenase, are the rate limiting and regulatory enzymes of the
citric acid cycle.citric acid cycle.
One control point outside the cycleOne control point outside the cycle
– – The decarboxylation of pyruvate to acetyl-CoA is The decarboxylation of pyruvate to acetyl-CoA is
irreversible.Therefore, it is critical that the reaction be regulated.irreversible.Therefore, it is critical that the reaction be regulated.

11. Summary of Materials and Products:Summary of Materials and Products:
Needed Materials:Needed Materials: Products:Products:
-Pyruvate -Pyruvate - 3 CO- 3 CO
22
-4NAD -4NAD - 4NADH- 4NADH
-FAD -FAD - FADH- FADH
22
-GDP -GDP - GTP- GTP
-Pi-Pi - 4H+- 4H+
-2 H-2 H
22OO

13. TCA and Amino Acid SynthesisTCA and Amino Acid Synthesis

14. TCA and Fatty Acid Synthesis

15. TCA and GluconeogenesisTCA and Gluconeogenesis

16. TCA cycle in catabolismTCA cycle in catabolism