2017 Biochemistry - Oxidation of Pyruvate and TCA Cycle Flashcards
Where does the pyruvate dehydrogenase complex “live” in the cell?
Inside the mitochondrion
How many enzymes and cofactors are involved in the PDH Complex?
3 Enzymes
- pyruvate dehydrogenase
- dihydrolipoyl transacetylase
- dihydrolipoyl dehydrogenase
5 Cofactors
- Thiamine pyrophosphate
- Lipoic acid
- Coenzyme A
- FAD
- NAD+
Where does the TCA cycle take place?
Matrix of Mitochondria
What are the inputs and outputs of the TCA cycle?
Inputs:
- Acetyl CoA
- H20
Outputs:
- 2-CO2
- 3-NADH
- FADH2
- GTP
What are the irreversible steps of TCA cycle and which enzymes are involved?
Step 1: Citrate Synthase
Step 6: a-Ketoglutarate dehydrogenase complex
What is the rate limiting step of TCA cycle? What is produced at this step?
Isocitrate dehydrogenase
Produces first NADH and first CO2
What inhibits Citrate synthase?
Succinyl-CoA
What stimulates and inhibits Isocitrate Dehydrogenase?
Stimulates: ADP
Inhibits: ATP
What inhibits a-KGDH?
Inhibits: Succinyl-CoA, NADH, GTP
What is the purpose of the pyruvate dehydrogenase multienzyme complex?
Oxidatively decarboxylate pyruvate into Acetyl-CoA
How many ATP molecules are produced per molecule of glucose using the TCA cycle?
Glycolysis: 8
PHD Complex: 6
TCA Cycle (only): 24
Total: 38 ATP
