Lipoxygenases ([intenz:1.13.11.-]) are a class of iron-containing dioxygenases which catalyses the hydroperoxidation of lipids, containing a cis,cis-1,4-pentadiene structure. They are common in plants where they may be involved in a number of diverse aspects of plant physiology including growth and development, pest resistance, and senescence or responses to wounding. Lipoxygenases can be classified as 9- and 13-lipoxygenases, according to the position of oxygen incorporation in linoleic acid and linolenic acid, the most important substrates for LOX catalysis in plants. There are six A. thaliana lipoxygenases identified: AtLOX1-6, among which AtLOX-1 and AtLOX-5 are 9S-lipoxygenases, and AtLOX-2, AtLOX-3, AtLOX-4 and AtLOX-6 are 13S-lipoxygenases [].
Lysyl oxidase () (LOX) []is an extracellular copper-dependent enzyme that catalyses the oxidative deamination of peptidyl lysine residues in precursors of various collagens and elastins, yielding alpha-aminoadipic-delta-semialdehyde. The deaminated lysines are then able to form semialdehyde cross-links, resulting in the formation of insoluble collagen and elastin fibres in the extracellular matrix [].The active site of LOX resides towards the C terminus: this region also binds a single copper atom in an octahedral coordination complex involving at least 3 His residues []. Four histidine residues are clustered in a central region of the enzyme. This region is thought to be involved in cooper-binding and is called the 'copper-talon' [].
This is the PLAT/LH2 domain of plant lipoxygenase related proteins. Lipoxygenases are nonheme, nonsulfur iron dioxygenases that act on lipid substrates containing one or more (Z,Z)-1,4-pentadiene moieties. In plants, the immediate products are involved in defense mechanisms against pathogens and may be precursors of metabolic regulators [, , ]. The generally proposed function of PLAT/LH2 domains is to mediate interaction with lipids or membrane bound proteins [].Lipoxygenases can be classified as 9- and 13-lipoxygenases, according to the position of oxygen incorporation in linoleic acid and linolenic acid, the most important substrates for LOX catalysis in plants. There are six A. thaliana lipoxygenases identified: AtLOX1-6, among which AtLOX-1 and AtLOX-5 are 9S-lipoxygenases, and AtLOX-2, AtLOX-3, AtLOX-4 and AtLOX-6 are 13S-lipoxygenases [].
