Carnitine is necessary for transport of long-chain fatty acids into mitochondria, to enter the beta-oxidation cycle. Four carnitine cycle defects have been described. The carnitine transporter mediates carnitine transport across the plasma membrane. Symptoms include hypoketotic hypoglycaemia and cardiomyopathy. Some affected subjects are asymptomatic. Newborn screening detects very low levels o...

The authors investigated 32 patients with the muscle form of CPT II deficiency. Total carnitine palmitoyltransferase enzyme system (CPT) activity was normal but abnormally inhibited by malonyl-CoA, palmitoyl-CoA, and the detergents Triton X and Tween 20. Mutation analysis identified three described mutations (S113L, P50H, and F448L) and two novel mutations (M214T and Y479F). Using modeling tech...

Continuous assays of carnitine palmitoyltransferase were used to study the hysteretic behaviour of the enzyme. When reactions were started by adding mitochondria to complete reaction mixtures, there was a lag in the assay even in the absence of malonyl-CoA. When mitochondria were preincubated with malonyl-CoA in the absence of palmitoyl-CoA, there was a greater lag period in the assay of carnit...

Inhibition of the overt mitochondrial carnitine palmitoyltransferase by malonyl-CoA is important in the regulation of fatty acid oxidation. In the past, the contribution of peroxisomal carnitine acyltransferase activity to the generation of medium- and long-chain acylcarnitines in the cytoplasm has been ignored. On the basis of marker enzyme levels, we now estimate that peroxisomal palmitoyltra...

We studied the effects of L-carnitine on growth performance, carcass composition, and lipid metabolism in male broilers. Six hundred male commercial broilers were allotted to five groups, each of which included three replicates (40 birds per replicate). The groups received the same basal diet supplemented with 0, 25, 50, 75, or 100 mg/kg L-carnitine, respectively. The feeding trial showed that ...

Malonyl-CoA inhibits the carnitine-dependent transport of activated fatty acids into mitochondria by inhibiting the outer carnitine palmitoyltransferase (McGarry et al., 1978). Recent studies in several laboratories have shown that malonyl-CoA is not an ordinary competitive inhibitor of the enzyme. Liver mitochondria from fasted or diabetic rats are less inhibited by malonyl-CoA than are mitoch...