The role of the carnitine system in peroxisomal fatty acid oxidation

Peroxisomes are small, subcellular organelles that play a major role in lip id metabolism. Inherited disorders of peroxisomal structure and metabolism can result from defective assembly, missing protein import transporters, or individual enzyme deficiencies. Molecular studies helped by the range of d isorders have now elucidated many of the pathways, including the paths of a -oxidation for phytanic acid and P-oxidation for very-long-chain and branch ed-chain fatty acids and for bile acid synthesis. The mechanism of the tran sfer of substrates, intermediates, and products across the membrane is poor ly understood. The carnitine system, known to transport activated acyl grou ps between localized coenzyme A pools, is presented. The evidence for the i nvolvement of carnitine in the transfer of activated acyl groups to and fro m the peroxisomes is reviewed.