The carnitine shuttle. l carnitine and acetyl l carnitine enter the Download Scientific Diagram L carnitine is primarily synthesized in the liver from the amino acids lysine and methionine through a series of four enzymatic reactions, with the liver and kidneys converting the precursor butyrobetaine into active L Carnitine Linus Pauling Institute Oregon State University (PDF) The Role of l Carnitine in Mitochondria, Prevention of Metabolic Inflexibility and Disease Initiation L Carnitine Linus Pauling Institute Oregon State University