Hydroperoxide lyase

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Hydroperoxide lyase
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EC no. 4.2.99.-
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Hydroperoxide lyases are enzymes that catalyze the cleavage of C-C bonds in the hydroperoxides of fatty acids. They belong to the cytochrome P450 enzyme family (CYP74C and CYP74B). [1]

Polyunsaturated fatty acids such as linolenic and linoleic acids are susceptible to formation of hydroperoxides upon contact with oxygen in air. Hydroperoxides are highly reactive functional groups since they contain an oxidant (O-O bond) adjacent to a reductant (C-H bonds). When flanked by olefins, the hydroperoxides can be induced to rearrange to give the hemiacetal. It is this reaction that is catalyzed by hydroperoxide lyases. The resulting aldehydes are notable as fragrances, green leaf volatiles, and antifeedants. [2]

An illustrative transformation involving a hydroperoxide lyase. Here cis-3-hexenal is generated by conversion of linolenic acid to the hydroperoxide by the action of a lipoxygenase followed by the lyase-induced formation of the hemiacetal. LyaseNonenalHemiAc.png
An illustrative transformation involving a hydroperoxide lyase. Here cis-3-hexenal is generated by conversion of linolenic acid to the hydroperoxide by the action of a lipoxygenase followed by the lyase-induced formation of the hemiacetal.

Related Research Articles

<span class="mw-page-title-main">CYP2E1</span> Protein-coding gene in the species Homo sapiens

Cytochrome P450 2E1 is a member of the cytochrome P450 mixed-function oxidase system, which is involved in the metabolism of xenobiotics in the body. This class of enzymes is divided up into a number of subcategories, including CYP1, CYP2, and CYP3, which as a group are largely responsible for the breakdown of foreign compounds in mammals.

<span class="mw-page-title-main">Lipoxygenase</span>

Lipoxygenases (LOX) are a family of (non-heme) iron-containing enzymes, more specifically oxidative 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 diverse 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.

<span class="mw-page-title-main">Hydroperoxide</span> Class of chemical compounds

Hydroperoxides or peroxols are compounds of the form ROOH, where R stands for any group, typically organic, which contain the hydroperoxy functional group. Hydroperoxide also refers to the hydroperoxide anion and its salts, and the neutral hydroperoxyl radical (•OOH) consist of an unbond hydroperoxy group. When R is organic, the compounds are called organic hydroperoxides. Such compounds are a subset of organic peroxides, which have the formula ROOR. Organic hydroperoxides can either intentionally or unintentionally initiate explosive polymerisation in materials with unsaturated chemical bonds.

Any enzyme system that includes cytochrome P450 protein or domain can be called a P450-containing system.

Omega oxidation (ω-oxidation) is a process of fatty acid metabolism in some species of animals. It is an alternative pathway to beta oxidation that, instead of involving the β carbon, involves the oxidation of the ω carbon. The process is normally a minor catabolic pathway for medium-chain fatty acids, but becomes more important when β oxidation is defective.

<span class="mw-page-title-main">CYP17A1</span> Mammalian protein found in Homo sapiens

Cytochrome P450 17A1 is an enzyme of the hydroxylase type that in humans is encoded by the CYP17A1 gene on chromosome 10. It is ubiquitously expressed in many tissues and cell types, including the zona reticularis and zona fasciculata of the adrenal cortex as well as gonadal tissues. It has both 17α-hydroxylase and 17,20-lyase activities, and is a key enzyme in the steroidogenic pathway that produces progestins, mineralocorticoids, glucocorticoids, androgens, and estrogens. More specifically, the enzyme acts upon pregnenolone and progesterone to add a hydroxyl (-OH) group at carbon 17 position (C17) of the steroid D ring, or acts upon 17α-hydroxyprogesterone and 17α-hydroxypregnenolone to split the side-chain off the steroid nucleus.

<span class="mw-page-title-main">Vernolic acid</span> Chemical compound

Vernolic acid is a long chain fatty acid that is monounsaturated and contains an epoxide. It is the R,R-cis epoxide derived from the C12–C13 alkene of linoleic acid. Vernolic acid was first definitively characterized in 1954. It is a major component in vernonia oil, which is produced in abundance by the genera Vernonia and Euphorbia and is a potentially useful biofeedstock.

The enzyme hydroperoxide dehydratase (EC 4.2.1.92) catalyzes the chemical reaction

<span class="mw-page-title-main">CYP2C18</span> Protein-coding gene in the species Homo sapiens

Cytochrome P450 2C18 is a protein that in humans is encoded by the CYP2C18 gene.

<span class="mw-page-title-main">CYP4A11</span> Protein-coding gene in the species Homo sapiens

Cytochrome P450 4A11 is a protein that in humans is codified by the CYP4A11 gene.

<span class="mw-page-title-main">CYP4F8</span> Protein-coding gene in the species Homo sapiens

Cytochrome P450 4F8 is a protein that in humans is encoded by the CYP4F8 gene.

<span class="mw-page-title-main">CYP4F12</span> Protein-coding gene in the species Homo sapiens

Cytochrome P450 4F12 is a protein that in humans is encoded by the CYP4F12 gene.

<span class="mw-page-title-main">CYP4F3</span> Protein-coding gene in the species Homo sapiens

Cytochrome P450 4F3, also leukotriene-B(4) omega-hydroxylase 2, is an enzyme that in humans is encoded by the CYP4F3 gene. CYP4F3 encodes two distinct enzymes, CYP4F3A and CYP4F3B, which originate from the alternative splicing of a single pre-mRNA precursor molecule; selection of either isoform is tissue-specific with CYP3F3A being expressed mostly in leukocytes and CYP4F3B mostly in the liver.

<span class="mw-page-title-main">CYP4F22</span> Protein-coding gene in the species Homo sapiens

CYP4F22 is a protein that in humans is encoded by the CYP4F22 gene.

<span class="mw-page-title-main">CYP4A22</span> Protein-coding gene in the species Homo sapiens

CYP4A22 also known as fatty acid omega-hydroxylase is a protein which in humans is encoded by the CYP4A22 gene.

<span class="mw-page-title-main">Oxylipin</span> Class of lipids

Oxylipins constitute a family of oxygenated natural products which are formed from fatty acids by pathways involving at least one step of dioxygen-dependent oxidation. These small polar lipid compounds are metabolites of polyunsaturated fatty acids (PUFAs) including omega-3 fatty acids and omega-6 fatty acids. Oxylipins are formed by enyzmatic or non-enzymatic oxidation of PUFAs.

Fatty-acid peroxygenase is an enzyme with systematic name fatty acid:hydroperoxide oxidoreductase (RH-hydroxylating). This enzyme catalyses the following chemical reaction

<span class="mw-page-title-main">Epoxyeicosatetraenoic acid</span> Chemical compound

Epoxyeicosatetraenoic acids are a set of biologically active epoxides that various cell types make by metabolizing the omega 3 fatty acid, eicosapentaenoic acid (EPA), with certain cytochrome P450 epoxygenases. These epoxygenases can metabolize EPA to as many as 10 epoxides that differ in the site and/or stereoisomer of the epoxide formed; however, the formed EEQs, while differing in potency, often have similar bioactivities and are commonly considered together.

Cytochrome P450 omega hydroxylases, also termed cytochrome P450 ω-hydroxylases, CYP450 omega hydroxylases, CYP450 ω-hydroxylases, CYP omega hydroxylase, CYP ω-hydroxylases, fatty acid omega hydroxylases, cytochrome P450 monooxygenases, and fatty acid monooxygenases, are a set of cytochrome P450-containing enzymes that catalyze the addition of a hydroxyl residue to a fatty acid substrate. The CYP omega hydroxylases are often referred to as monoxygenases; however, the monooxygenases are CYP450 enzymes that add a hydroxyl group to a wide range of xenobiotic and naturally occurring endobiotic substrates, most of which are not fatty acids. The CYP450 omega hydroxylases are accordingly better viewed as a subset of monooxygenases that have the ability to hydroxylate fatty acids. While once regarded as functioning mainly in the catabolism of dietary fatty acids, the omega oxygenases are now considered critical in the production or break-down of fatty acid-derived mediators which are made by cells and act within their cells of origin as autocrine signaling agents or on nearby cells as paracrine signaling agents to regulate various functions such as blood pressure control and inflammation.

The Schenck ene reaction or the Schenk reaction is the reaction of singlet oxygen with alkenes to yeild hydroperoxides. The hydroperoxides can be reduced to allylic alcohols or eliminate to form unsaturated carbonyl compounds. It is a type II photooxygenation reaction, and is discovered in 1944 by Günther Otto Schenck. Its results are similar to ene reactions, hence its name.

References

  1. Grechkin AN, Brühlmann F, Mukhtarova LS, Gogolev YV, Hamberg M (2006). "Hydroperoxide lyases (CYP74C and CYP74B) catalyze the homolytic isomerization of fatty acid hydroperoxides into hemiacetals". Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids. 1761 (12): 1419–28. doi:10.1016/j.bbalip.2006.09.002. PMID   17049304.
  2. Matsui K (2006). "Green leaf volatiles: hydroperoxide lyase pathway of oxylipin metabolism". Current Opinion in Plant Biology. 9 (3): 274–80. doi:10.1016/j.pbi.2006.03.002. PMID   16595187.

Further reading