Question

If a lcfa is synthesized with isotopically labeled carbons at the c2 and c3 positions, in which product(s) of the initial cycle of its β-oxidation will an isotopically-labeled carbon be found?

Answer 1

The isotopically-labeled carbon will be found in the two first acetyl CoA products (the C2 carbon of the first acetyl CoA and the C1 carbon of the second acetyl CoA).

Β-oxidation is the main metabolic pathway of degradation of fatty acid molecules to produce:

on the one hand acetyl-CoA, whose acetyl group is oxidized by the Krebs cycle

and on the other hand NADH and FADH2, whose high potential electrons feed the respiratory chain.

In eukaryotic cells, β-oxidation takes place aerobically in the mitochondrial matrix, but also in other organelles such as peroxisomes and, in plants, glyoxysomes.