6 An undergraduate student is studying a rare purple tailed

6. An undergraduate student is studying a rare purple tailed squirrel. She adds excess radiolabeled fatty acids to the cytosol of liver cells but no radiolabeled fatty acyl-CoA is detected in the mitochondrial matrix. A very low inorganic phosphate concentration is detected in the cytosol as well as a high concentration of free coenzyme A. When radiolabeled fatty acyl-camitine was added to the intermembrane space of mitochondria, it was later detected in the mitochondrial matrix. The quaternary structure of carnitine acyltransferase I was found to be intact. Explain what is wrong with this squirrel. Propose an experiment to test your hypothesis

Solution

Fatty acids are activated to acyl CoA by thiokinases. The reaction occurs in two steps and requires ATP, coenzyme A and Mg2+. Fatty acid reacts with ATP to form acyladenylate which then combines with coenzyme A to produce acyl CoA.

Two high energy phosphates are utilized, since ATP is converted to pyrophosphate (PPi). The enzyme inorganic
pyrophosphafase hydrolyses PPi to phosphate Pi.

This process are basic for B-oxidation of fatty acids.

Carnitine acyl transerase I carries the fatty acids to inner mitochondrial membrane through specific carrier protein.

Hypothesis

In this experiment Carnitine acyl transerase I is not functional in the squirrel or mutated and seen Carnitine acyl transerase I is responsible to carry the Acyl CoA from cytosol to mitochondrial matrix.

Carnitine acyl transerase I is mutated and addtion of radiolabelled fatty acid is converted to acyl CoA in cytosol and result in accumulation of inorganic phosphate due to this process. Fatty acid not transfer into the matrix due to the mutation of Carnitine acyl transerase I.

When Carnitine acyl transerase I is added fatty acid istransfer into the matrix. It concluded Carnitine acyl transerase I is responsible for carry acyl CoA from cytosol to matrix.