Question

For fatty acid synthesis what would be the substrate if you are making an even number fatty acid?

What would be the product if you are breaking down an odd number fatty acid?

Answer 1

Answer – Fatty acid synthesis begins with one Acetyl-CoA to acetyl-ACP y the enzyme acetyl transferase and another Acetyl-CoA getting converted to Malonyl-CoA and then to Malonyl-ACP by the enzymes Acetyl-CoA carboxylase and Malonyl transferase respectively. Then, fatty acid synthase carries out first the condensation of acetyl-ACP and Malonyl-ACP forming Aceto acetyl-ACP and then following downstream steps even number fatty acid. Cycle repeats but the end product of last cycle condense with Malonyl-ACP to extend the fatty acid chain. Thus, for fatty acid synthesis, the substrate would be Acetyl-CoA and Malonyl-CoA.

While breaking down an odd number of fatty acid, the whole chain gets break downs to Acetyl-CoA and Propionyl-CoA molecule. Propionyl-CoA is further catabolize and converted to Succinyl-CoA which can be used as intermediate in Krebs’s cycle. Thus, Acetyl-CoA and Succinyl-coA will be the product while breaking down odd number fatty acid.

Therefore, for fatty acid synthesis Acetyl-CoA and Malonyl-CoA would be the substrate if you are making an even number fatty acid. Acetyl-CoA and Succinyl-coA would be the product if you are breaking down an odd number fatty acid.