palmitoylcarnitine

Palmitoylcarnitine, also called palmitoyl-L-carnitine, is an acylcarnitine formed by the esterification of palmitic acid with carnitine. It is one of several long-chain acylcarnitines that participate in the transport of fatty acids into mitochondria for beta-oxidation.

In mitochondria, the outer membrane enzyme carnitine palmitoyltransferase I (CPT1) transfers the palmitoyl group from palmitoyl-CoA to carnitine, producing palmitoylcarnitine. The acylcarnitine is shuttled across the inner membrane by the carnitine-acylcarnitine translocase (CACT), where CPT2 re-forms palmitoyl-CoA for beta-oxidation. This shuttle allows long-chain fatty acids to be oxidized efficiently, and palmitoylcarnitine can also be exported from mitochondria under certain conditions.

Physiologically, the levels of palmitoylcarnitine and other acylcarnitines reflect fatty acid oxidation flux and mitochondrial function. Abnormal elevations can indicate defects in beta-oxidation or carnitine transport, such as fatty acid oxidation disorders or metabolic stress. Measurement of acylcarnitines, including palmitoylcarnitine, is used in newborn screening and in metabolic investigations to assess fatty acid oxidation capacity.

Analytically, palmitoylcarnitine is routinely measured as part of acylcarnitine profiling by tandem mass spectrometry in plasma or dried blood spots. Levels are influenced by fasting status, diet, and disease state; interpretation requires consideration of clinical context.