The Enzyme Database

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Accepted name: acyl-lipid (11-3)-desaturase
Reaction: (1) an (11Z,14Z)-icosa-11,14-dienoyl-[glycerolipid] + 2 ferrocytochrome b5 + O2 + 2 H+ = an (8Z,11Z,14Z)-icosa-8,11,14-trienoyl-[glycerolipid] + 2 ferricytochrome b5 + 2 H2O
(2) an (11Z,14Z,17Z)-icosa-11,14,17-trienoyl-[glycerolipid] + 2 ferrocytochrome b5 + O2 + 2 H+ = an (8Z,11Z,14Z,17Z)-icosa-8,11,14,17-tetraenoyl-[glycerolipid] + 2 ferricytochrome b5 + 2 H2O
Glossary: di-homo-γ-linolenate = (8Z,11Z,14Z)-icosa-8,11,14-trienoate
Other name(s): acyl-lipid 8-desaturase; Δ8 fatty acid desaturase; Δ8-desaturase; Δ8-fatty-acid desaturase; efd1 (gene name); D8Des (gene name); phytosphinganine,hydrogen donor:oxygen Δ8-oxidoreductase (incorrect); SLD
Systematic name: acyl-lipid,ferrocytochrome b5:oxygen oxidoreductase [(11-3),(11-2)-cis-dehydrogenating]
Comments: The enzyme, characterized from the protist Euglena gracilis [1] and the microalga Rebecca salina [2], introduces a cis double bond at the 8-position in 20-carbon fatty acids that are incorporated into a glycerolipid and have an existing Δ11 desaturation. The enzyme is a front-end desaturase, introducing the new double bond between the pre-existing double bond and the carboxyl-end of the fatty acid. It contains a cytochrome b5 domain that acts as the direct electron donor to the active site of the desaturase, and does not require an external cytochrome. Involved in alternative pathways for the biosynthesis of the polyunsaturated fatty acids arachidonate and icosapentaenoate.
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc
1.  Wallis, J.G. and Browse, J. The Δ8-desaturase of Euglena gracilis: an alternate pathway for synthesis of 20-carbon polyunsaturated fatty acids. Arch. Biochem. Biophys. 365 (1999) 307–316. [DOI] [PMID: 10328826]
2.  Zhou, X.R., Robert, S.S., Petrie, J.R., Frampton, D.M., Mansour, M.P., Blackburn, S.I., Nichols, P.D., Green, A.G. and Singh, S.P. Isolation and characterization of genes from the marine microalga Pavlova salina encoding three front-end desaturases involved in docosahexaenoic acid biosynthesis. Phytochemistry 68 (2007) 785–796. [DOI] [PMID: 17291553]
[EC created 2008, modified 2015]

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