Synthesis of acyl-S-pantetheine by rat liver microsomes

The synthesis of acyl-S-pantetheine was found to occur in rat liver microsomal preparations. The reaction required ATP and a metal ion as cofactors, a fatty acid and the reduced form of pantetheine for optimal activity. The K_m for pantetheine was 0.8 mM, for ATP 0.8 mM, and for oleic acid 0.3 mM. Mg²⁺ (20 mM), Mn²⁺ (5 mM), Ca²⁺ (5 mM), and Fe²⁺ (5 mM) produced approximately equal activity when all other conditions were optimal. The characterization of the product and other properties of the enzyme are described. The acyl-S-pantetheine formed does not act as an acyl donor in the acylation ofsn-glycerol-3-phosphate, 1,2-diacylglycerol, or lysolecithin.