Pyruvate Oxidation Flashcards
Is pyruvate oxidation aerobic or anaerobic?
Aerobic
What type of cells don’t use aerobic metabolism at all?
Red blood cells, they only carry oxygen
Where does pyruvate oxidation occur?
Mitochondrial matrix
What enzyme converts pyruvate into acetyl-CoA?
Pyruvate dehydrogenase complex (PDC)
How many carbons does acetyl-CoA have?
2
What type of reaction does the PDC catalyze?
Oxidative decarboxylation
What is the oxidizing agent used for pyruvate oxidation?
NAD+
What are the 4 cofactors besides NAD+ involved in the PDC?
TPP, lipoic acid, FAD, and Mg2+
What is the first step of pyruvate oxidation?
The carboxyl group in pyruvate gets cleaved off and released as CO2. What’s left gets attached to TPP
What is the second step of pyruvate oxidation?
The hydroxyethyl group is transferred to the lipoic acid swinging arm as an acetyl group
What is the third step of pyruvate oxidation?
The acetyl group is transferred to coenzyme A to form acetyl-CoA
What is the fourth step of pyruvate oxidation?
Regeneration of the swinging arm
Why is PDC such an efficient enzyme?
- Lots of copies of each enzyme, so lots of active sites
2. The swinging arm delivers each intermediate to the next active site
What is the process of bringing an intermediate to the next active site called?
Substrate channelling
Why is PDC tightly regulated?
It controls the rate of aerobic metabolism and the entry of glucose into the citric acid cycle
What happens to acetyl-CoA when there’s too much?
It gets sent through fatty acid synthesis
How is PDC regulated?
The ratio of NAD+ to NADH, amount of ATP, amount of acetyl-CoA
What happens to the rate of PDC when there is lots of NAD+?
It speeds up
What happens to the rate of PDC when there is lots of NADH?
It slows down
What happens to the rate of PDC when there is lots of ATP?
It slows down
What happens to the rate of PDC when there is lots of ADP?
It speeds up
What happens to the rate of PDC when there is lots of acetyl-CoA?
It slows down from product inhibition
