What is essential for transfer of fatty acid across mitochondrial membrane –
Correct Answer: Carnitine
Description: Ans. is 'c' i.e., Carnitine o Formation of acyl Co A (activated fatty acid) takes place in the cytosol,o Further degradation occurs in the mitochondrial matrix.o This creates a problem because the inner mitochondral membrane is impermeable to long chain acyl CoA (activated fatty acid).o To overcome this problem, participation of a carrier, carnitine is required Q,o It is Synthesized from lysine Q and methionine in liver and kidney.o The transport process, referred to as carnitine shuttle, comprises following steps: -The acyl group af acyl CoA is transferred to carnitine, resulting in formation of fatty acylcamitine. The reaction is catalyzed by rate-limiting enzyme of b-oxidation, carnitine acyl transferase-1: CAT-1 (or carnitine palmitoyltransferase-1), which is located on outer side (cytosolic side) of inner mitochondrial membrane or inner side of outer mitochond rial membrane QAcylcamitine is able to penetrate the inner membrane Q and is transported across the inner mitochondrial membrane by an enzyme translocase (camitine-acylcamitine translocase). Entry of acylcamitine is coupled with exit of carnitine.Once inside the mitochondrial matrix, acyl group of acylcamitine is transferred back to CoA by the enzyme carnitine acyl transferase-11: CAT-11 (or carnitine palmitoyl transferase-11) located on the inside of the inner mitochondrial membrane. Acyl-CoAis reformed in mitochondrial matrix with liberation of carnitine which is returned to the cytosalic side by the translocase (camitine-acylcamitine translocase) in exchange for an incoming acylcamitine.
Category:
Biochemistry
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