KEGG   ENZYME: 1.14.19.4Help
Entry
EC 1.14.19.4                Enzyme                                 

Name
acyl-lipid (11-3)-desaturase;
acyl-lipid 8-desaturase;
Delta8 fatty acid desaturase;
Delta8-desaturase;
Delta8-fatty-acid desaturase;
efd1 (gene name);
D8Des (gene name);
phytosphinganine,hydrogen donor:oxygen Delta8-oxidoreductase (incorrect);
SLD
Class
Oxidoreductases;
Acting on paired donors, with incorporation or reduction of molecular oxygen;
With oxidation of a pair of donors resulting in the reduction of O2 to two molecules of water
BRITE hierarchy
Sysname
acyl-lipid,ferrocytochrome b5:oxygen oxidoreductase [(11-3),(11-2)-cis-dehydrogenating]
Reaction(IUBMB)
(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
Substrate
(11Z,14Z)-icosa-11,14-dienoyl-[glycerolipid];
ferrocytochrome b5 [CPD:C00999];
O2 [CPD:C00007];
H+ [CPD:C00080];
(11Z,14Z,17Z)-icosa-11,14,17-trienoyl-[glycerolipid]
Product
(8Z,11Z,14Z)-icosa-8,11,14-trienoyl-[glycerolipid];
ferricytochrome b5 [CPD:C00996];
H2O [CPD:C00001];
(8Z,11Z,14Z,17Z)-icosa-8,11,14,17-tetraenoyl-[glycerolipid]
Comment
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 Delta11 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.
History
EC 1.14.19.4 created 2008, modified 2015
Orthology
K21732  
acyl-lipid (11-3)-desaturase
Reference
1  [PMID:10328826]
  Authors
Wallis JG, Browse J.
  Title
The Delta8-desaturase of Euglena gracilis: an alternate pathway for synthesis of 20-carbon polyunsaturated fatty acids.
  Journal
Arch. Biochem. Biophys. 365 (1999) 307-16.
  Sequence
Reference
2  [PMID:17291553]
  Authors
Zhou XR, Robert SS, Petrie JR, Frampton DM, Mansour MP, Blackburn SI, Nichols PD, Green AG, Singh SP
  Title
Isolation and characterization of genes from the marine microalga Pavlova salina  encoding three front-end desaturases involved in docosahexaenoic acid biosynthesis.
  Journal
Phytochemistry. 68 (2007) 785-96.
  Sequence
Other DBs
ExplorEnz - The Enzyme Database: 
IUBMB Enzyme Nomenclature: 
ExPASy - ENZYME nomenclature database: 
BRENDA, the Enzyme Database: 

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