Lipoxygenases: occurrence, functions, catalysis, and acquisition of substrate.

Lipoxygenase reactions may initiate the synthesis of a signaling molecule or be involved in inducing structural or metabolic changes in the cell. For signaling, synthesis of a single fatty acid hydroperoxide is required. For inducing structural changes, synthesis of a particular product may not be so important as the ability to induce what amounts to an enzyme-catalyzed lipid peroxidation. Reflecting these different functions are lipoxygenases with different characteristics in catalysis. There are enzymes that tightly control the reaction with molecular oxygen and others that form mixed products and permit the release of free radicals. In this review the diversity of lipoxygenase expression will be highlighted and the several facets of lipoxygenase function considered, concluding with a discussion of issues related to the acquisition of substrate in a cellular environment.