Krebs Cycle
1 Krebs Cycle
Outline - Chapter 11 in Text
- Reactions of Pyruvate
- Formation of Oxaloacetate
- Formation of Acetyl-CoA
- Reactions of Krebs Cycle
- Regulation of Krebs Cycle
2 Pyruvate to Oxaloacetate
| ®  |
- Pyruvate ® Oxaloacetate
- First step in gluconeogenesis
- Requires CO2
3 Pyruvate to Acetyl-CoA
- Reaction occurs inside mitochondria
- Partial Net Reaction:
CH3 -C(O)-COO - ® CH3 -C(O)-S-CoA + CO2 - Pyruvate oxidized: Oxidative decarboxylation
- Lipoic acid undergoes reduction of disulfide group
- Dihydrolipoic acid + FAD ® lipoic acid + FADH2
4 Pyruvate Dehydrogenase
Pyruvate Dehydrogenase Complex contains three 'enzyme activities', with multiple copies of each.
- E. Coli - 24, 24, & 12 copies in a single complex
- Mammals - (20-30), 60, & (20-30) copies
5 Krebs Cycle reactions
Net Reaction:
| Acetyl-CoA | 2 CO2 + CoA | |
| GDP + Pi | ® | GTP + H2O |
| 3 NAD + + FAD | 3 NADH + 3 H + + FADH2 |
6 Regulation of Krebs Cycle
7 Citrate Metabolism
- High [citrate] in cytosol only if cell's energy requirements are low.
- Acetyl-CoA and NADPH used for fatty acid synthesis
File translated from TEX by TTH, version 3.02.
On 8 Apr 2002, 13:44.