Question

it has been observed that malonyl-CoA inhibits palmitic acid oxidation in isolated mitochondria, but that it has little or no effect on the oxidation of octanoic acid ( C8, saturated). Explain this observation.

Answer 1

In the cytosol acetyl-CoA is converted to malonyl CoA catalyzed by acetyl CoA carboxylase. As
malonyl CoA inhibits CPT I, it leads to prevention of long chain fatty acids but not short chain/medium chain fatty acids from adding carnitine and prevents its transport to mitochondrial matrix. Since octanoic acid (C8, saturated) is short chain fatty acid, therefore, malonyl-CoA inhibits palmitic acid oxidation in isolated mitochondria, but that it has little or no effect on the oxidation of octanoic acid