Effect of carboxylic acid xenobiotics and their metabolites on the activity of carnitine acyltransferases

Salicylyl-CoA and benzoyl-CoA were good inhibitors of carnitine acetyltransferase (CAT), competing with acetyl-CoA with K(i) values of 7.5 and 22 μM respectively in the forward direction and with CoA in the reverse reaction with similar K(i) values. They were also competitive inhibitors of carnitine octanoyltransferase (K(i) = 261 and 295 μM respectively), but were only weakly inhibitory to carnitine palmitoyltransferase. Inhibition of energy production by salicylate may result from the inhibition of CAT by salicylyl-CoA.