In three separate experiments of Krebs cycle, pyruvate labeled with 14 C at C-1, at C-2, or at C-3 is metabolized via the pyruvate dehydrogenase complex and the citric acid cycle.
a.Which labeled pyruvate molecule is the first to yield 14 CO2 ?
b.Which is the last to yield 14 CO2 ?
c.How many turns of the cycle are required to release all of the labeled carbon atoms as 14 CO2 ?
Pyruvate—three carbons—is converted to acetyl CoA, a two-carbon molecule attached to coenzyme A. A molecule of coenzyme A is a necessary reactant for this reaction, which releases a molecule of carbon dioxide and reduces a NAD+ to NADH.