Chpt 17 Flashcards
Pyruvate Oxidation
- Aerobic Conditions
- pyruvate enters in matrix of mitochondria
- irreversible
- preserves free energy of decarboxylation, and free energy is used to reduced NAD+ and NADH and attach Acetyl group to CoA forming Acetyl CoA
What enzyme catalyzes Pyruvate Oxidation?
-characteristics
Pyruvate Dehydrogenase-Multisubunit Enzyme
E1- Pyruvate Dehydrogenase
-oxidative decarboxylation of pyruvate
-Prosthetic Group- Thiamine Pyrophosphate
E2-Dihydrolipoyl Transacetylase
- transfer of acetyl group to CoA
- Prosthetic Group- Lipoic acid (lipoamide)
- Cofactor- CoA
E3- Dihydrolipoyl Dehydrogenase
- Regeneration of Oxidized form of Lipoamide
- Prosthetic Group-FAD
- Coenzyme- NAD+
What does Pyruvate Dehydrogenase Produce as end products?
Acetyl-CoA and CO2 at the expense of NAD+ to NADH
Regulation of Pyruvate Dehydrogenase bifunctional enzyme
Stimulators: (low energy charge)
Dephosphorylation
ADP
pyruvate
Inhibitors: (High energy charge) Phosphoryation ATP Acetyl CoA NADH
Thiamine Pyrophosphate
- Helper molecule
- Function
- Vitamin
- deficiency
Prosthetic Group of E1-Pyruvate Dehydrogenase
- Function- Aldehyde group carrier
- Vitamin- Thiamine (B1)
- Deficiency-BeriBeri (weight loss, neurological disfunction, heart problems)
Lipoid Acid
- Helper molecule
- Function
- Vitamin
- deficiency
Prosthetic Group of E2-Dihydrolipoyl Transacetylase and attaches to R group of Lysine
- Function- acyl group carrier
- Vitamin-Lipoid Acid
E1
- reaction type
- Helper Molecule
Pyruvate Dehydrogenase subunit of Pyruvate Dehydrogenase bifunctional Enzyme:
- Oxidative decarboxylation of pyruvate
- Prosthetic Groups- TPP-Thiamine Pyrophosphate
Eukaryotic Regulation:
1) High Energy=kinase active=Phosphorylation=E1 inactive
- High NADH, Acetyl CoA, and ATP
2) Low Energy charge=phosphatase on=dephosphorylation=E1 active
E1 mechanism
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