(3 of 5) Pyruvate dehydrogenase complex is a large enzyme complex comprised of 3
ID: 302542 • Letter: #
Question
(3 of 5) Pyruvate dehydrogenase complex is a large enzyme complex comprised of 3 subunits and a number of coenzymes. Which of the following statements regarding this enzyme is true? O The redox reaction this enzyme catalyzes stores free energy in a thioester bond. O Lipoate, one of the enzymes coenzymes, is a lipid derivative that participates in redox chemistry via a disulfide bond. O Contains FAD that undergoes a reduction and oxidation prior to the end of the catalytic mechanism. O Decarboxylates pyruvate. All of the above.Explanation / Answer
(3 of 5) B. Lipoate, one of the enzymes coenzyme, a lipid derivative that participates in a redox chemistry via a disulfide bond.
Lipoic acid or lipoate acts as coenzyme for Dihydrolipoyl ttransactional.Pyruvate dehydrogenase (E1) catalyses the decarboxylation of pyruvate, it produces hydroxyethyl-TPP, and oxidised hydroxyethyl-TPP group to acetyl group. The electrons from this oxidation reduce lipoate bound to Dihydrolipoyl transacetylase (E2). Dihydrolipoyl dehydrogenase (E3) again regenerates the disulfide form of lipoate.
(4 of 5) C. The 2nd phase leads to the production of 6 mols of NADH, leading to 15 mols of ATP, per every 1 mol of glucose oxidised.
There are 3 phases for complete glucose oxidation. 1. Glycolysis, 2. Krebs cycle or TCA cycle and 3. Electron Transport Chain. In the 2nd phase or TCA cycle 1 mol of pyruvate produces 3 mols of NADH, and as 2 mols of pyruvates are produced in glycolysis so total 6 mols of NADH are produced in 2nd phase. In the presence of oxygen, one mol of NADH oxidized to yield 2.5 mols of ATP. So 6 mols NADH will produce total (2.5×6)=15 mols of ATP.
(5 of 5) D. In the case of succinyl-Co, leads to substrate level phosphorylation.
Substrate level phosphorylation is a process in which ATP is formed as a result of the oxidation of an organic compound (substrate) without participation of any electron donor or electron acceptor. The cleavage of the thioester bond of succinyl-CoA is coupled with the phosphorylation of GDP or ADP.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.