GO:0016717 "oxidoreductase activity, acting on paired donors, with oxidation of a pair of donors resulting in the reduction of molecular oxygen to two molecules of water" evidence=IEA
GO:0016717 "oxidoreductase activity, acting on paired donors, with oxidation of a pair of donors resulting in the reduction of molecular oxygen to two molecules of water" evidence=IEA
>cd03507 Delta12-FADS-like The Delta12 Fatty Acid Desaturase (Delta12-FADS)-like CD includes the integral-membrane enzymes, delta-12 acyl-lipid desaturases, oleate 12-hydroxylases, omega3 and omega6 fatty acid desaturases, and other related proteins, found in a wide range of organisms including higher plants, green algae, diatoms, nematodes, fungi, and bacteria
The expression of these proteins appears to be temperature dependent: decreases in temperature result in increased levels of fatty acid desaturation within membrane lipids subsequently altering cell membrane fluidity. An important enzyme for the production of polyunsaturates in plants is the oleate delta-12 desaturase (Arabidopsis FAD2) of the endoplasmic reticulum. This enzyme accepts l-acyl-2-oleoyl-sn-glycero-3-phosphocholine as substrate and requires NADH:cytochrome b oxidoreductase, cytochrome b, and oxygen for activity. FAD2 converts oleate(18:1) to linoleate (18:2) and is closely related to oleate 12-hydroxylase which cat
>cd03506 Delta6-FADS-like The Delta6 Fatty Acid Desaturase (Delta6-FADS)-like CD includes the integral-membrane enzymes: delta-4, delta-5, delta-6, delta-8, delta-8-sphingolipid, and delta-11 desaturases found in vertebrates, higher plants, fungi, and bacteria
These desaturases are required for the synthesis of highly unsaturated fatty acids (HUFAs), which are mainly esterified into phospholipids and contribute to maintaining membrane fluidity. While HUFAs may be required for cold tolerance in bacteria, plants and fish, the primary role of HUFAs in mammals is cell signaling. These enzymes are described as front-end desaturases because they introduce a double bond between the pre-exiting double bond and the carboxyl (front) end of the fatty acid. Various substrates are involved, with both acyl-coenzyme A (CoA) and acyl-lipid desaturases present in this CD. Acyl-lipid desaturases are localized in the membranes of cyanobacterial thylakoid, plant endoplasmic reticulum (ER), and plastid; an
>PF00487 FA_desaturase: Fatty acid desaturase This entry is only a subset of the Pfam family
; InterPro: IPR005804 Fatty acid desaturases are enzymes that catalyse the insertion of a double bond at the delta position of fatty acids. There seem to be two distinct families of fatty acid desaturases which do not seem to be evolutionary related. Family 1 is composed of: Stearoyl-CoA desaturase (SCD) (1.14.19.1 from EC) []. Family 2 is composed of: Bacterial fatty acid desaturases. Plant stearoyl-acyl-carrier-protein desaturase (1.14.19.1 from EC) [], this enzyme catalyzes the introduction of a double bond at the delta(9) position of steraoyl-ACP to produce oleoyl-ACP. This enzyme is responsible for the conversion of saturated fatty acids to unsaturated fatty acids in the synthesis of vegetable oils. Cyanobacterial DesA [], an enzyme that can introduce a second cis double bond at the delta(12) position of fatty acid bound to membranes glycerolipids. DesA is involved in chilling tolerance; the phase transition temperature of lipids of cellular membranes being dependent on the degree of unsaturation of fatty acids of the membrane lipids. This entry contains fatty acid desaturases belonging to Family 1. ; GO: 0006629 lipid metabolic process
>cd03511 Rhizopine-oxygenase-like This CD includes the putative hydrocarbon oxygenase, MocD, a bacterial rhizopine (3-O-methyl-scyllo-inosamine, 3-O-MSI) oxygenase, and other related proteins
It has been proposed that MocD, MocE (Rieske-like ferredoxin), and MocF (ferredoxin reductase) under the regulation of MocR, act in concert to form a ferredoxin oxygenase system that demethylates 3-O-MSI to form scyllo-inosamine. This domain family appears to be structurally related to the membrane fatty acid desaturases and the alkane hydroxylases. They all share in common extensive hydrophobic regions that would be capable of spanning the membrane bilayer at least twice. Comparison of sequences also reveals the existence of three regions of conserved histidine cluster motifs that contain eight histidine residues: HXXXH, HXXHH, and HXXHH. These histidine residues are reported to be catalytically essential and proposed to be the ligands for the iron atoms contained within homologs, stearoyl CoA d
>cd03510 Rhizobitoxine-FADS-like This CD includes the dihydrorhizobitoxine fatty acid desaturase (RtxC) characterized in Bradyrhizobium japonicum USDA110, and other related proteins
Dihydrorhizobitoxine desaturase is reported to be involved in the final step of rhizobitoxine biosynthesis. This domain family appears to be structurally related to the membrane fatty acid desaturases and the alkane hydroxylases. They all share in common extensive hydrophobic regions that would be capable of spanning the membrane bilayer at least twice. Comparison of sequences also reveals the existence of three regions of conserved histidine cluster motifs that contain eight histidine residues: HXXXH, HXX(X)HH, and HXXHH. These histidine residues are reported to be catalytically essential and proposed to be the ligands for the iron atoms contained within homologs, stearoyl CoA desaturase and alkane hydroxylase.
>COG3239 DesA Fatty acid desaturase [Lipid metabolism]
>cd03514 CrtR_beta-carotene-hydroxylase Beta-carotene hydroxylase (CrtR), the carotenoid zeaxanthin biosynthetic enzyme catalyzes the addition of hydroxyl groups to the beta-ionone rings of beta-carotene to form zeaxanthin and is found in bacteria and red algae
Carotenoids are important natural pigments; zeaxanthin and lutein are the only dietary carotenoids that accumulate in the macular region of the retina and lens. It is proposed that these carotenoids protect ocular tissues against photooxidative damage. CrtR does not show overall amino acid sequence similarity to the beta-carotene hydroxylases similar to CrtZ, an astaxanthin biosynthetic beta-carotene hydroxylase. However, CrtR does show sequence similarity to the green alga, Haematococcus pluvialis, beta-carotene ketolase (CrtW), which converts beta-carotene to canthaxanthin. Sequences of the CrtR_beta-carotene-hydroxylase domain family, as well as, the CrtW_beta-carotene-ketolase domain family appear to be structurally related
>cd03513 CrtW_beta-carotene-ketolase Beta-carotene ketolase/oxygenase (CrtW, also known as CrtO), the carotenoid astaxanthin biosynthetic enzyme, initially catalyzes the addition of two keto groups to carbons C4 and C4' of beta-carotene
Carotenoids are important natural pigments produced by many microorganisms and plants. Astaxanthin is reported to be an antioxidant, an anti-cancer agent, and an immune system stimulant. A number of bacteria and green algae can convert beta-carotene into astaxanthin by using several ketocarotenoids as intermediates and CrtW and a beta-carotene hydroxylase (CrtZ). CrtW initially converts beta-carotene to canthaxanthin via echinenone, and CrtZ initially mediates the conversion of beta-carotene to zeaxanthin via beta-cryptoxanthin. After a few more intermediates are formed, CrtW and CrtZ act in combination to produce astaxanthin. Sequences of this domain family appear to be structurally related to membrane fatty acid desaturases and alkane hydroxylases. Th
>PF12073 DUF3553: Protein of unknown function (DUF3553); InterPro: IPR021938 This family of proteins is functionally uncharacterised
This protein is found in bacteria. Proteins in this family are about 60 amino acids in length. This protein has two conserved sequence motifs: GQVQS and TVNF.
>cd01060 Membrane-FADS-like The membrane fatty acid desaturase (Membrane_FADS)-like CD includes membrane FADSs, alkane hydroxylases, beta carotene ketolases (CrtW-like), hydroxylases (CrtR-like), and other related proteins
They are present in all groups of organisms with the exception of archaea. Membrane FADSs are non-heme, iron-containing, oxygen-dependent enzymes involved in regioselective introduction of double bonds in fatty acyl aliphatic chains. They play an important role in the maintenance of the proper structure and functioning of biological membranes. Alkane hydroxylases are bacterial, integral-membrane di-iron enzymes that share a requirement for iron and oxygen for activity similar to that of membrane FADSs, and are involved in the initial oxidation of inactivated alkanes. Beta-carotene ketolase and beta-carotene hydroxylase are carotenoid biosynthetic enzymes for astaxanthin and zeaxanthin, respectively. This superfamily domain has extensive hydrophobic regions that would
>cd03509 DesA_FADS-like Fatty acid desaturase protein family subgroup, a delta-12 acyl-lipid desaturase-like, DesA-like, yet uncharacterized subgroup of membrane fatty acid desaturase proteins found in alpha-, beta-, and gamma-proteobacteria
Sequences of this domain family appear to be structurally related to membrane fatty acid desaturases and alkane hydroxylases. They all share in common extensive hydrophobic regions that would be capable of spanning the membrane bilayer at least twice. Comparison of these sequences also reveals three regions of conserved histidine cluster motifs that contain eight histidine residues: HXXXH, HXXHH, and HXXHH. These histidine residues are reported to be catalytically essential and proposed to be the ligands for the iron atoms contained within homologs, stearoyl CoA desaturase and alkane hydroxylase.
