ExplorEnz: EC 1.14.19.25

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1.14.19.25

Accepted name:

acyl-lipid ω-3 desaturase (cytochrome b₅)

Reaction:

a linoleoyl-[glycerolipid] + 2 ferrocytochrome b₅ + O₂ + 2 H⁺ = an α-linolenoyl-[glycerolipid] + 2 ferricytochrome b₅ + 2 H₂O

Glossary:

linoleoyl-[glycerolipid] = (9Z,12Z)-octadeca-9,12-dienoyl-[glycerolipid]
α-linolenoyl-[glycerolipid] = (9Z,12Z,15Z)-octadeca-9,12,15-trienoyl-[glycerolipid]

Other name(s):

FAD3

Systematic name:

(9Z,12Z)-octadeca-9,12-dienoyl-[glycerolipid],ferrocytochrome b₅:oxygen oxidoreductase (15,16 cis-dehydrogenating)

Comments:

This microsomal enzyme introduces a cis double bond three carbons away from the methyl end of a fatty acid incorporated into a glycerolipid. The distance from the carboxylic acid end of the molecule does not have an effect. The plant enzyme acts on carbon 15 of linoleoyl groups incorporated into both the sn-1 and sn-2 positions of the glycerol backbone of phosphatidylcholine and other phospholipids, converting them into α-linolenoyl groups. The enzyme from the fungus Mortierella alpina acts on γ-linolenoyl and arachidonoyl groups, converting them into stearidonoyl and icosapentaenoyl groups, respectively [3]. cf. EC 1.14.19.35, sn-2 acyl-lipid ω-3 desaturase (ferredoxin).

Links to other databases:

BRENDA, EXPASY, Gene, KEGG, MetaCyc

References:

1.	Browse, J., McConn, M., James, D., Jr. and Miquel, M. Mutants of Arabidopsis deficient in the synthesis of α-linolenate. Biochemical and genetic characterization of the endoplasmic reticulum linoleoyl desaturase. J. Biol. Chem. 268 (1993) 16345–16351. [PMID: 8102138]
2.	Arondel, V., Lemieux, B., Hwang, I., Gibson, S., Goodman, H.M. and Somerville, C.R. Map-based cloning of a gene controlling ω-3 fatty acid desaturation in Arabidopsis. Science 258 (1992) 1353–1355. [DOI] [PMID: 1455229]
3.	Sakuradani, E., Abe, T., Iguchi, K. and Shimizu, S. A novel fungal ω³-desaturase with wide substrate specificity from arachidonic acid-producing Mortierella alpina 1S-4. Appl. Microbiol. Biotechnol. 66 (2005) 648–654. [DOI] [PMID: 15538555]

[EC 1.14.19.25 created 2015]