Please show your work and give a clear explanation: Determine the number of mole
ID: 786472 • Letter: P
Question
Please show your work and give a clear explanation:
Determine the number of moles of ATP derived from the complete aerobic metabolism of one mole of ribose-5-phosphate to CO2 (conversion to glycolysis intermediates, then glycolysis to pyruvate, then the Krebs cycle). Be careful with the stoichiometry -- the answer is not an integer! (Hint: Start with 3 moles of ribose-5-phosphate.) You may assume that the oxidation of each NADH in the ETS yields 2.5 ATP's. whether it's cytoplasmic or mitochondrial NADH. and that he oxidation of each reduced flavoprotein (E-FADH2) via ubiquinol (QH2) yields 1.5 ATP's. (Answer: 27-2/3)Explanation / Answer
The enzymes transketolase and transaldolase catalyze the rearrangement of three C5 sugars to two equivalents of fructose and one equivalent of glyceraldehyde. The stoichiometry of the overall reaction is:
2 Xylulose 5-phosphate + Ribose 5-phospate --->
2 Fructose 6-phosphate + Glyceraldehyde 3-phospate
The reaction proceeds in three steps through the intermediate sugars sedoheptulose 7-phosphate and erythrose 4-phosphate.
The two transformations catalyzed by transketolase move acyl carbanion fragments, which we previously encountered in the pyruvate dehydrogenase reaction. Nature uses the same chemistry here; the acyl carbanion fragments are stabilized by the catalytic cofactor thiamine pyrophosphate (TPP), which acts as an electron sink.