Inactivation of thromboxane synthase with hydroperoxy-fatty acids

Bovine lung thromboxane synthase was immobilized on phenyl-Sepharose beads by adsorption. The immobilized enzyme was catalytically active and synthesized both TXA2 and HHT. The structure-activity relationship of several hydroperoxy fatty acids and their ability to inactivate thromboxane synthase was investigated. Millimolar quantities of hydrogen peroxide and tert-butylperoxide were required to inactivate the enzyme: whereas micromolar quantities of C18 and C20 hydroperoxy fatty acids inactivated the enzyme. Pretreatment of the enzyme with long chain hydroperoxy-fatty acids resulted in a decreased synthesis of both TXB2 and HHT.