L-Carnitine CAS:541-15-1 L-Carnitine, an amino acid derivative, is found in nearly all cells of the body. It transports long-chain fatty acids across the inner mitochondrial membranes in the mitochondria, where they are processed by beta-oxidation to produce biological energy in the form of adenosine triphosphate or ATP. Used in the management of cardiac ischemia and peripheral arterial disease.