With anandamide as substrate plant 5-lipoxygenases behave like 11-lipoxygenases

Abstract

Anandamide, an endogenous ligand for cannabinoid receptors CB1 and CB2, was incubated with purified 5-lipoxygenases from barley and tomato. This yielded 11S-hydroperoxy-5,8,12,14-eicosatetraenoylethanolamide (11S-HPANA) as major product (about 70%). This is in contrast with the dioxygenation of arachidonic acid, where 5S-HPETE is the major product. This observation implies that the regiospecificity of the dioxygenation, catalyzed by nonmammalian 5-lipoxygenases, is altered by a modification at the carboxylic end of the substrate. Soybean 15-lipoxygenase forms 15S-HPANA (95%) and 11S-HPANA (5%), and in the second dioxygenation 5,15-diHPANA (45%) and 8,15-diHPANA (55%) are formed. Apparently, the regiospecificity of the soybean 15-lipoxygenase reaction is only slightly affected using anandamide as substrate.