ENZYME

ENZYME entry: EC 1.14.19.4

Accepted Name

Acyl-lipid (11-3)-desaturase.

Alternative Name(s)

Acyl-lipid 8-desaturase.

Delta(8)-desaturase.

SLD.

Reaction catalysed

An (11Z,14Z)-icosa-11,14-dienoyl-[glycerolipid] + 2 ferrocytochrome b5 + O(2) + 2 H(+) <=> an (8Z,11Z,14Z)-icosa-8,11,14-trienoyl-[glycerolipid] + 2 ferricytochrome b5 + 2 H(2)O
An (11Z,14Z,17Z)-icosa-11,14,17-trienoyl-[glycerolipid] + 2 ferrocytochrome b5 + O(2) + 2 H(+) <=> an (8Z,11Z,14Z,17Z)-icosa-8,11,14,17-tetraenoyl-[glycerolipid] + 2 ferricytochrome b5 + 2 H(2)O

Comment(s)

The enzyme, characterized from the protist Euglena gracilis and the microalga Rebecca salina, introduces a cis double bond at the 8-position in 20-carbon fatty acids that are incorporated into a glycerolipid and have an existing Delta(11) 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.

Cross-references

PROSITE

BRENDA

EC2PDB

ExplorEnz

PRIAM enzyme-specific profiles

KEGG Ligand Database for Enzyme Nomenclature