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45 Cards in this Set

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  • Back
The Pyruvate Dehydrogenase Complex provides Acetyl CoA to what?
TCA and fatty acid synthesis
The Pyruvate Dehydrogenase Complex is located where?
What overal reaction does Pyruvate Dehydrogenase Complex carry out?
Oxidative Decarboxylation
What are the three enzymes that make up the Pyruvate Dehydrogenase Complex?
1.) Pyruvate Decarboxylase
2.) Dihydrolipoyl Transacetylase
3.) Dihydrolipoyl Dehydrogenase.
What is the pyruvate dehydrogenase reaction equation?
Pyr + CoA + NAD+ <--> AcCoA + NADH + H+ + CO2
Pyruvate must be changed to what before entering TCA?
Acetyl CoA
T/F - The conversion of pyruvate to Acetyl CoA and CO2 is reversible.
F - It is irreversible.
Pyruvate Dehydrogenase Complex Mechanism
Pyruvate Dehydrogenase Complex Mechanism
Pyruvate Dehydrogenase Complex Mechanism
Pyruvate Dehydrogenase Complex Mechanism
Pyruvate Dehydrogenase Complex Mechanism
After decarboxylation, the hydroxyethyl intermediate will bind to what?
Thiamine pyrophosphate
TPP is attached to, and a coenzyme of what enzyme?
Pyruvate Decarboxylase (E1)
What happens to the hydroxylethyl intermediate after it is transferred to lipoic acid.
Becomes oxidized (-C=O)
What must happen to the lipoic acid before it receives the acetyl group?
Must be in reduced form (-SH)
Lipoic Acid attached to the lysine residue is called what?
Lipoic acid belongs to which PDH enzyme?
Dihydrolipoyl transacetylase (E2)
The acetyl group bound as a thioester (-C(=O)-S-Lipoic Acid) is transferred to where?
What is the final acetyl acceptor?
The sulfhydryl form of lipoic acid is oxidized by what?
FAD+ is on what which enzyme?
Dihydrolipoyl dehydrogenase (E3)
FADH2 is oxidized by what?
NAD+ located on dihydrolipoyl dehydrogenase.
What does NAD+ do in the Pyruvate Dehydrogenase mechanism?
Oxidizes FADH2, then dissociate from the complex.
Thiazolium Ring
What is this called?
Lipoamide is a dithiol which is subject to what type of reaction?
CoA is a derivative what?
What is the reactive group in CoA?
Thiol group
What is a catalytic cycle?
Following the substrate reaction, where the enzymes and coenzymes are regenerated by more enzymatic steps.
What are the five coenzymes of PDH Complex?
1.) TPP
2.) Lipoate
3.) NAD+
4.) FAD+
5.) CoA
What vitamin provides TPP
What vitamin provides for CoA
What vitamin provides for FAD
What vitamin provides for NAD
What are the mechanisms regulating Pyruvate Dehydrogenase Complex activity?
1.) Product feedback inhibition
2.) Inactivation by phosphorylation
What enzyme will phosphorylate the PDH complex into inactive form?
What are the allosteric activators of kinase
1.) NADH
2.) Acetyl CoA
What are the allosteric inhibitors of kinase
1.) ADP
2.) Pyruvate
3.) CoA
4.) NAD
What enzyme will dephosphorylate the PDH complex into active form?
What are some medical conditions associated with PDH complex?
1.) Thiamine deficiency (dietary)
2.) Pyruvate DH deficiency (genetic)
3.) Shock - tissue hypoxia leads to shut down of PDH complex
What are some symptoms associated with Thiamine Deficiency?
1.) Elevated serum pyruvate
2.) Reduced pyruvate oxidation (critical for brain)
3.) Loss of neural function
What are some diseases associated with Thiamine Deficiency (diet)?
1.) Alcoholism
2.) Beri Beri
PyrDH deficiency has what kind of symptoms?
1.) Elevated serum pyruvate, alanine, lactate
2.) Defective catalytic or regulatory subunit
When is PyrDH deficiency detected?
During childhood
What are some diseases associated with PyrDH deficiency?
Chronic Lactic Acidosis