Purification of carnitine acetyltransferase from skeletal muscle of the camel (Camelus dromedarius)

The enzyme carnitine acetyltransferase (CAT) catalyzes the reversible transfer of short-chain acyl groups between coenzyme A and L-carnitine, and hence, plays an important role in the beta-oxidation of fatty acids. Purification and characterization of CAT from desert animal species may help in explaining the involvement of secondary pathways for energy production in these species. In this paper, we report the purification and partial characterization of CAT from the Arabian camel. CAT was purified from the skeletal muscle of the Arabian camel by ammonium sulfate and acetone fractionation, followed by chromatography on DEAE-Sepharose, agarose-Co A and Superose 12 gel filtration columns. CAT was purified by 2937-fold to a specific activity of 94 Units mg(-1). The purified CAT was a monomer of 59 kDa as judged by native and SDS-PAGE, and showed a pi of 5.2. The enzyme displayed maximum activity with propionyl-Co A. Apparent K-m for acetyl-, propionyl- and butyryl-Co A were 27.7, 17.3 and 29 mu M respectively, while palmitoyl-Co A was not a substrate.