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