ABSTRACT
Lipoxygenases are enzymes that catalyze a stereospecific dehydrogenation and subsequent dioxygenation of polyunsaturated fatty acids with a 1,4-cis-pentadiene structure. The reaction leads to formation of a hydroperoxide, containing a 1-hydroperoxy-2-trans-4-cis-pentadiene fragment. Considering the substrate arachidonic acid, oxygen may consequently be introduced at six different positions, yielding 5-, 8-, 9-, 11-, 12-, and 15-hydroperoxy-eicosatetraenoic acid (HPETE), in which the number indicates the position of the respective hydroperoxy group (1). In most biological systems, the hydroperoxide undergoes reduction into the corresponding monohydroxy acid (HETE) either nonenzymatically or by a peroxidase-catalyzed reaction. The stereospecificity exhibited by mammalian lipoxygenases leads to oxygenated derivatives in which the resulting substituent is in the S configuration.
