ABSTRACT
Carnitine serves as a cofactor for several enzymes, including carnitine translocase and acylcarnitine transferases I and II, which are essential for the movement of activated long-chain fatty acids from the cytoplasm into the mitochondria (Figure 11.2). The translocation of fatty acids (FAs) is critical for the generation of adenosine triphosphate (ATP) within skeletal muscle, via
β
-oxidation. These activated FAs become esterified to acylcarnitines with carnitine via carnitine-acyl-transferase I (CAT I) in the outer mitochondrial membrane. Acylcarnitines can easily permeate the membrane of the mitochondria and are translocated across the membrane by carnitine translocase. Carnitine’s actions are not yet complete because the mitochondrion has two membranes to cross; thus, through the action of CAT II, the acylcarnitines are converted back to acyl-CoA and carnitine. Acyl-CoA can be used to generate ATP via
β
-oxidation, Krebs cycle, and the electron transport chain. Carnitine is recycled to the cytoplasm for future use.
