Which of the following is incorrect concerning allosteric regulation of the pyruvate dehydrogenase complex? Choose one:A. E3 (Dihydrolipoyl dehydrogenase) is allosterically regulated by NADH.B. The NADH-NAD+ ratios indicate the levels of ATP production.C. E2 (Dihydrolipoyl acetyltransferase) is allosterically regulated by acetyl-CoA.D. E1 (Pyruvate dehydrogenase) is allosterically regulated by ATP.
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Step 1
The PDC consists of three main enzymes: E1 (Pyruvate dehydrogenase), E2 (Dihydrolipoyl acetyltransferase), and E3 (Dihydrolipoyl dehydrogenase). Each of these enzymes has specific regulatory mechanisms. Show more…
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The following statements are correct about the reaction catalyzed by the pyruvate dehydrogenase complex EXCEPT: The activity of the complex is regulated by the phosphorylation of pyruvate dehydrogenase (E1) NAD+ is the direct oxidant of reduced lipoamide Although E1 (pyruvate dehydrogenase) is called "pyruvate dehydrogenase" it is not a dehydrogenase An FAD is covalently linked to the dihydrolipoyl dehydrogenase (E3) It is the link between glycolysis and the TCA cycle Citrate synthase is a ___ with binding of ___ inducing a conformational change ___ the binding of acetyl-CoA, and ___ is an allosteric inhibitor. dimer; OAA; increasing; NADH dimer; OAA; decreasing; NADH tetramer; OAA; decreasing; NAD+ monomer; pyruvate; decreasing; ATP monomer; pyruvate; increasing; ATP
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The pyruvate dehydrogenase complex is inhibited by high levels of NADH. What is the best explanation for this regulatory step? a. None of these are accurate statements regarding NADH inhibition of PDH. b. NADH binds to an allosteric site on the E1 enzyme and blocks the first step. c. When NADH is high, NAD+ is low, so E3 and lipoamide are not returned to their active oxidized state. d. NADH will reduce lipoamide, thus inactivating the enzyme. e. NADH reduces the acyl lipoic lysine to hydroxyethyl lipoic lysine, which can no longer transfer the acyl-group.
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Which of the following inhibits the pyruvate dehydrogenase complex? A. ATP B. Pyruvate [stimulates] C. Acetyl CoA D. NADH E. A, C and D
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