Question

On what carbon atoms does the ¹⁴CO₂, used to synthesize malonyl-CoA from acetyl-CoA appear in palmitate?

Short answer

The ¹⁴C label does not appear in the palmitate.

Step-by-step solution

Palmitate

A fatty acid with a 16-carbon chain is called palmitic acid or hexadecanoic acid in IUPAC nomenclature.It is the most prevalent saturated fatty acid in all living things, including humans, animals, and plants.

Beta-ketoacyl-ACP-synthase

The enzyme $\beta$-ketoacyl-ACP synthase is involved in the production of fatty acids. This enzyme uses malonyl-CoA as a carbon source to elongate the ACP-bound acyl species.

Step 2: Carbon atoms on which 14CO2 used to synthesize malonyl-CoA

The acetyl group from ACP is transferred to the Cys residue by $\beta$-ketoacyl-ACP synthase. The malonyl-ACP is then decarboxylated in the second phase, resulting in the loss of ¹⁴C labeled CO₂.

As a result, the ¹⁴C label does not appear in the palmitate.