Substrate Down Regulation of 12-lipoxygenase in Human Platelets

Lipoxygenases are non heme iron containing enzymes which catalyze dioxygenation of unsaturated fatty acids with the production of the corresponding hydroperoxides. The main mammalian lipoxygenases are classified with respect to the positional specificity of the oxygenation of arachidonic acidI. 12-Lipoxygenase (12-LO) from human platelets was the first mammalian lipoxygenase described2however, the biological significance of this pathway in platelets is not completely understood. Furthermore, little is known about regulation of 12-lipoxygenase activity in human platelets. It has been shown that 12-LO is activated by its product, 12-hydroperoxyeicosatetraenoic acid (12-HPETE)3.