Question

Glycolysis, the TCA cycle and oxidative phosphorylation are tightly coupled by allosteric inhibition or stimulation of various enzymes in the pathways. Among the compounds that act as inhibitors or stimulators are glucose 6-phosphate, ADP, AMP, Pi (inorganic phosphate ion), ATP, citrate, NADH, and succinyl-CoA. For as many steps in the pathways as you can, indicate which enzymes or reactions are inhibited or stimulated by which of the compounds listed. A given enzyme reaction may be stimulated or inhibited by more than one compound, and a given compound may affect more than one reaction.

            For each correctly indicated enzyme-compound pair you will receive two points up to a maximum of ten pairs. For each incorrectly indicated pair, you will lose one point. Your score will be the net of gain minus loss! If you can’t remember the name of an enzyme, you may name instead its substrate(s) and product(s).

NO diagrams or structures needed

Answer 1

1. Citrate synthase is inhibited by ATP, NADH, and succinyl CoA.
2. lsocitrate dehydrogenase is activated by ADP, and inhibited by ATP and NADH.
3. Alpha-Ketoglutarate ehydrogenasies inhibited by succinyl CoA and NADH.
4. PDH kinase activate by ATP, NADH, Acetyl CoA.
5. AMP activates protein kinase to inhibit pyrvate kinase b.
6. ADP, AMP and Pi activate frutose 2,6 bisphasphatase enzyme.
7. ATP, Citrate inhibits phosphofructose kinase enzyme.
8. Glyceraldehyde 3 phosphate activated by pi.
9. Prruvate kinase inhibited by by ATP and activated by F1,6-BP.
10. Hexokinase activate by ATP.