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Reading Guide, Stryer Short Course, Chapter 18
1. In the presence of oxygen, pyruvate is converted into a molecule called ______________.
2. From the schematic of figure 18.2, it is observed that the acetyl unit of acetyl CoA enters the
citric acid cycle and is converted to ________.
3. What is the name of the enzyme that catalyzes the conversion of pyruvate to acetyl CoA? This
___________________ conversion of pyruvate into acetyl CoA is the linke between
___________ and ______________. This reaction is a decisive reaction in metabolism: it
commits the carbon atoms of carbohydrates to ______________________________
or_____________________________________.
4. The pyruvate dehydrogenase complex is actually made up of _____ enzymes and requires
____ cofactors.
5. The catalytic cofactors of this complex are _______________, ____________________, and
______________. The two stoichiometric cofactors are ___________________________.
6. Which cofactor is necessary for the decarboxylation?
7. Which cofactor is involved in redox and also forms a thioester?
8. In the process, FAD is reduced to _____________ as lipoamide is reoxidized. In turn,
_______________ is reoxidized to FAD as NAD+ is reduced to ________________.
9. Which cofactor also serves as a flexible linkage to bring the substrate to all the enzyme active
sites?
10. Looking at Figure 18.7, describe the mechanism with reference to each subunit and role of
each cofactor.
11. Pyruvate dehydrogenase complex is highly regulated because
_____________________________________________________________________.
12. PDC is allosterically regulated by product inhibition through the compounds
________________________ and ______________________.
13. The key means of regulation of PDC in eukaryotes is ________________________. At high
energy charge, a kinase shuts down PDC. At low energy charge, a _____________________ is
activated, which reactivates PDC by hydrolyzing a phosphate ester. If this enzyme is deficient,
glucose must always take the anaerobic path leading to ______________________.
14. Beriberi is a vitamin deficiency that results in lack of the cofactor _______________. Why
does this deficiency lead to neurological disease?