Lipoxygenases are a family of non-heme, iron-containing enzymes most of which catalyze the dioxygenation of polyunsaturated fatty acids in lipids containing a cis,cis-1,4-pentadiene into cell signaling agents that serve various roles as autocrine signals that regulate the function of their parent cells, paracrine signals that regulate the function of nearby cells, and endocrine signals that regulate the function of distant cells. Human proteins expressed from the lipoxygenase family include ALOX12, ALOX12B, ALOX15, ALOX15B, ALOX5, and ALOXE3. While humans also have the ALOX12P2 gene, which is an ortholog of the well-expressed Alox12P gene in mice, the human gene is a pseudogene; consequently, ALOX12P2 protein is not detected in humans.
The typical lipoxygenase catalyzes the following reaction:The lipoxygenases are related to each other based upon their similar genetic structure and dioxygenation activity. However, one lipoxygenase, ALOXE3, while containing a lipoxygenase genetic structure, possesses relatively little dioxygenation activity; rather its primary activity appears to be as an isomerasewhich catalyzes hydroperoxy unsaturated fatty acids into their 1,5-epoxide, hydroxyl derivatives.
Lipoxygenases are found in plants, fungi, and animals; while the third domain of terrestrial life, the archaea, possesses proteins with a slight amino acid sequence similarity (~20%) to lipoxygenases, these proteins lack iron-binding residues and therefore are not projected to possess lipoxygenase activity.
These enzymes are most 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. In mammals a lot of lipoxygenasesisozymes are involved in the metabolism of eicosanoids (such as prostaglandins, leukotrienes and nonclassic eicosanoids).Two lipoxygenases may act in series to produce di-hydroxy or tri-hydroxy products that have activities quite different than either lipoxyenases' products. This serial metabolism may take place in different cell types that express only one of the two lipoxygenases in such a process termed transcellular metabolism. As an example, ALOX5 and ALOX15 or, alternatively, ALOX5 and ALOX12 can act serially to metabolizearachidonic acid into lipoxins while ALOX15 and possibly ALOX15B can act with ALOX5 to metabolize eicosapentaenoic acid to resolvin D's.
Currently, a reliable and reproducible method using highly sensitive LC-MS/MS platform for the identification and quantification of diverse lipoxygenase products (eicosanoids) in different sample types has been established by the scientists at Creative Proteomics, which can satisfy the needs of academic and industrial study in your lab.
Identification and quantification oflipoxygenase productsby mixed organic solvent extractionin plasma or tissue. Lipoxygenase products are extracted and concentrated using solid phase extraction. The eluant is dried and re-suspended for LC-MS separation and measured using MRM methods.
Representative lipoxygenase products that can be measured in a Lipoxygenase Product Panel by targeted LC-MS/MS:
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