Problem 22
Chemistry of Malic Enzyme: Variation on a Theme Malic enzyme, found in the bundle-sheath cells of \(\mathrm{C}_{4}\) plants, carries out a reaction that has a counterpart in the citric acid cycle. What is the analogous reaction? Explain your choice.
Problem 24
Inorganic Pyrophosphatase The enzyme inorganic pyrophosphatase contributes to making many biosynthetic reactions that generate inorganic pyrophosphate essentially irreversible in cells. By keeping the concentration of \(P P_{i}\) very low, the enzyme "pulls" these reactions in the direction of PP formation. The synthesis of ADP-glucose in chloroplasts is one such reaction. However, the synthesis of UDP-glucose in the plant cytosol, which also produces \(P P_{1}\), is readily reversible in vivo. How do you reconcile these two facts?
