Question

If the carbons at the 1 and 3 positions in glycerol are radiolabeled with 14C, and glycerol is metabolized in the human liver via glycolyisis and the TCA cycle, what are the fates of these labeled carbons after the first and second round of the TCA cycle? Is the label completeley lost? If so, after how many cycles? Indicate the label with an asterisk (*). Your answer must include CHEMICAL STRUCTURES that track the label at every step, and a brief RATIONALE for any unusual distribution of the label. Names of enzymes and substrates ARE also required.

Answer 1

After one round of the citric acid cycle, the label emerges in C-2 and C-3 of oxaloacetate and the label emerges in CO₂ in the formation of acetyl CoA from pyruvate after one and second round of the citric acid the label emerges in c-1 and c-4 of oxaloacetate.
G’ for the complete oxidation of the acetyl unit of acetyl
CoA by the citric acid cycle.
-41 kJmol-1 or -9.8 kcalmol-.
Malate dehydrogenase is the enzyme.