Study Questions for Exam
3
Study Question Set 18
Pyruvate
Dehydrogenase
| Lehninger |
Chapter 16 |
Problems |
10d, 11, 24 |
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| Osgood |
Chapter 15 |
Topics |
7, 41, 42 |
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Chapter 16 |
Topics |
1-8 |
Additional Questions
- Describe the role of TTP in the pyruvate decarboxylase reaction in cells
performing alcohol fermentation, giving the details of steps in the "activation"
of pyruvate for decarboxylation.
- Describe the role of TPP in the oxidative decarboxylation of pyruvate by
pyruvate dehydrogenase.
- The tutorial on TPP-based decarboxylations at the "Interactive Biochemistry"
web site at the University of Virginia, Charlottesville http://cti.itc.Virginia.EDU/~cmg
does an excellent job of helping you understand the first reaction catalyzed
by the Pyruvate Dehydrogenase Complex. Click on "Contents" to get the selection
list. Go to "Enzyme Mechanisms", and then select "Acetolactate
Synthase Mechanism Tutorial". Follow the interactive tutorial through
the decarboxylation step -- the sequence is identical to that in pyruvate
dehydrogenase. You might also find it an interesting
challenge to complete the rest of the interactive drill leading to the synthesis
of acetolactate.
- Describe the role of the lipoamide prosthetic group of dihydrolipoyl transacetylase
in the oxidation of the hydroxyethyl-TPP complex of the pyruvate dehydrogenase
complex.
- Describe the formation of acetyl Co-A at the active site of pyruvate dehydrogenase.
- Describe the sequence of steps involved in reoxidation of dihydrolipoate
to lipoate in the lipoamide portion of E2 of the pyruvate dehydrogenase complex.
- Explain why it is necessary for the NAD+-dependent dihydrolipoyl
dehydrogenase component of the pyruvate dehydroagenase complex to be a flavoprotein.
- Describe the composition of the pyruvate dehydrogenase complex of E. coli.
- Compare this composition to the composition of the enzyme in mammalian mitochondria.
- What is the advantage of such an elaborate organization of the complex
pyruvate dehydrogenase complex to the organism?
- Describe the attachment of the lipoic acid prosthetic group at the active site of E2 in the pyruvate dehydrogenase complex. How does this attachment facilitate the reaction catalyzed by the entire complex?
- What is the advantage of having multiple lipoamide chains per dihydrolipoyl transacetylase molecule in pyruvate dehydrogenase?
Last Study Question Set for Exam 3
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