Formation of leukotriene B4-coenzyme A ester by rat liver microsomes.

When leukotriene B4 (LTB4) was incubated with rat liver microsomal fraction in the presence of coenzyme A (CoA) and ATP, a more polar product (compound I) was detected on reverse-phase high-performance liquid chromatography (RP-HPLC). The product was identified as LTB4-CoA ester on the basis of ultraviolet spectrometry, alkaline hydrolysis followed by RP-HPLC, and fast atom bombardment mass spectrometry (FAB-MS). The activity forming LTB4-CoA ester was localized in the microsomal fraction. The reaction was proportional to the concentration of the microsomal protein with an optimal pH of 7.5-8.0 and completely dependent on CoA and ATP. Palmitic acid and myristic acid significantly inhibited the formation.