Please explain Pathway of Carbon in Fatty Acid Synthesis Usi

Please explain

Pathway of Carbon in Fatty Acid Synthesis Using your knowledge of fatty add biosynthesis, provide an explanation for the following experimental observations: Addition of uniformly labeled |^14C|acetyl-CoA to a soluble liver fraction yields palmitate uniformly labeled with^14C. However, addition of a trace of uniformly labeled |^14C|acetyl-CoA in the presence of an excess of unlabeled malonyl-CoA to a soluble liver fraction yields palmitate labeled with^14C only in C-15 and C-16.

Solution

Part-a: the loading of acyl carrier protein (ACP) is going to need “acetyl-CoA” and addition of malonyl Co-A. So that this malonyl Co-A resultant product of acetyl Co-A with CO2 in the presence of acetyl-CoA carboxylase. Therefore, addition of uniformly labeled [14C]acetyl-CoA is going to produce malonyl Co-A (labeling can be found at C1 & C2) finally generate a labeled palmitate

Part-b: However, addition of a trace of uniformly labeled [14C]acetyl-CoA in the presence of an excess of unlabeled malonyl-CoA becuae of the “non-labled metabolic product of malonyl-CoA. The [14C] labeled acetyl-CoA is going to get loaded to acyl carrier protein so that these are going to yield plamitate with labeling found at C-15 and C-16 instead of formation of malonyl-CoA. Here, this process is known as “a slow, rate-controlling process”. Apart from this, any kind of labeled malonyl-CoA may be undergoes dilution during higher amount of unlabeled malonyl-CoA