Accepted_test

The main source of oxylipins in plants is the lipoxygenase cascade, which begins with the formation of hydroperoxides by lipoxygenases (LOXs). Lipoxygenases are non-heme iron- or manganese-containing enzymes that catalyze the regio- and stereospecific peroxidation of unsaturated fatty acids containing the (1Z,4Z)-pentadiene system resulting in the formation of the corresponding hydroperoxides. Lipoxygenases were found in animals, plants, fungi and bacteria, algae, and cyanobacteria. Typical substrates of plant lipoxygenases are linoleic and α-linolenic acids. LOX products, fatty acid hydroperoxides, are substrates for a number of enzymes, including reductases, peroxygenases, and cytochromes P450 of the CYP74 family. In this case, there is an obvious paradox, that there are several times fewer enzymes for the further conversion of hydroperoxides, the diversity of which reaches at least seven, than the lipoxygenases themselves. For example, cucumber has only four CYP74 enzymes and thirty lipoxygenases. Moreover, until recently, the entire variety of lipoxygenases was reduced only to 9- and 13-specific lipoxygenases, differing in the carbon atom within linoleic or alpha-linolenic acids, which they oxidize. This study is aimed at explaining this paradox.