Properties of partially purified carnitine acetyltransferase.

Subsequent reports from our laboratory showed that both carnitine (/3-hydroxy-y-trimethylammonium butyrate) and acetylcarnitinei increased oxygen uptake and oxidation of long chain fatty acids by heart homogenates incubated under conditions optimal for fatty acid oxidation (2, 3). Acetylcarnitine action could not be attributed simply to formation of carnitine via hydrolysis because acetylcarnitine addition augmented respiration in the absence of added coenzyme A (CoA) whereas carnitine had no such effect (3). Further, acetylcarnitine enhanced the conversion of (Y-labeled fatty acids to COZ in the absence of CoA to a greater extent than carnitine did. The possibility that carnitine acetyltransferase and other transferases might be directly involved in mediating the metabolic effects of carnitine on fatty acid metabolism has been discussed in previous publications (3-5). In the present investigation we shall describe the properties of carnitine acetyltransferase and will give results demonstrating that the 0-acyl structure of acylcarnitine derivatives has a high group potential.