This project investigates the biochemical and molecular basis of human carnitine palmityltransferase (CPT) deficiency, a hereditary muscle disease that causes exercise intolerance and is one of the principal causes of recurrent exertional myoglobinuria. The two forms of the enzyme, CPT-A and CPT-B, will be purified from the inner membrane of human mitochondria, obtained from liver and muscle at autopsy. A simplified purification procedure has been devised from preliminary studies with rat liver CPT-A; similar methods will be applied to the purification of CPT-B solubilized in Triton X-100. The physical, enzymatic and immunological properties of the two forms of CPT will be compared, and the relation between CPT in various human tissues will be determined. The results will indicate whether or not CPT-A and CPT-B are structurally identical, whether isoenzymes of CPT exist in different tissues, and if so, whether they share a common subunit.