Free palmitate is activated to its coenzyme A derivative (palmitoyl-CoA) in the cytosol before it can be oxidized in the mitochondrion. If palmitate and [14C]coenzyme A are added to a liver homogenate, palmitoyl-CoA isolated from the cytosolic fraction is radioactive, but the palmitoyl-CoA isolated from the mitochondrial fraction is not. Why is this?

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Biology

20 May, 04:16

Free palmitate is activated to its coenzyme A derivative (palmitoyl-CoA) in the cytosol before it can be oxidized in the mitochondrion. If palmitate and [14C]coenzyme A are added to a liver homogenate, palmitoyl-CoA isolated from the cytosolic fraction is radioactive, but the palmitoyl-CoA isolated from the mitochondrial fraction is not. Why is this?

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Biggie · Answer 1

The fatty acyl group condensed with CoA in the cytosol is first transferred to carnitine, releasing CoA and then transported to the mitochondrion, where it is condensed with CoA again. CoA cytosolic and mitochondrial pools are therefore kept separate and no radioactive CoA enters the mitochondrion from the cytosolic pool.