CAC- PDC Flashcards
What is the CAC?
A series of eight reactions, oxidising the acetyl groups of acetyl CoA to two CO2, converting the liberated free energy into the reduced compounds NADH and FADH2.
What does one complete cycle of CAC yield?
Two CO2, Three NADH, one FADH2 and one GTP.
What is the reaction pathway of CAC?
3 NAD+ + FAD + GDP + Pi + Acetyl CoA —-> 3NADH+ FADH2 + GTP + CoA + 2 CO2
What happens to the oxaloacetate used in the first step?
It is regenerated in the last one, thus can oxidise unlimited number of acetyl gruop.
Where are all CAC enzymes found?
In the mitochondria.
What is required of acetyl group oxidation to the two CO2?
Transfer of four electron pairs, accounted for by reduction of 3 NAD+ to 3 NADH and reduciton of FAD to FADH2.
Where is the free energy from acetyl group oxidation conserved?
NADH and FADH2
What is the end-product of anaerobic and aerobic glycolysis?
Anaerobic is lactate, whilst pyruvate is aerobic.
Multienzyme Complexes
Protein complexes where two or more sequential steps are catalysed.
Why are enzymatic reaction rates increased in multienzyme complexes?
Usually enzyme reaction rates ae limited by frequency in which enzymes collide with their substrates, in ME , the distance the sequential steps occur is reduced, limining need for chance collision.
How do ME complexes minimise side reactions?
Reduced distance between enzymes reduces chance for metabolic intermediates produced reaction with other molecules.
Pyruvate Dehydrogenase Complex
Forms acetyl-CoA from pyruvate through oxidative carboxylation
Oxidative Decarboxylation
A reaction where a carboxylate group is removed, forming CO2.
What are the three enzymes in the PDC?
Pyruvate Dehydrogenase, Dihydrolipoyl Transacetylase and Dihydrolipoyl dehydrogenase.
Stoichiometry of PDC?
Pyruvate + CoA + NAD+ —-> acetyl-CoA + CO2 + NADH