EC 1.14.19.75     
Accepted name: very-long-chain acyl-lipid ω-9 desaturase
Reaction: (1) 1-hexacosanoyl-2-acyl-[phosphoglycerolipid] + 2 ferrocytochrome b5 + O2 + 2 H+ = 1-[(17Z)-hexacos-17-enoyl]-2-acyl-[phosphoglycerolipid] + 2 ferricytochrome b5 + 2 H2O
(2) 1-tetracosanoyl-2-acyl-[phosphoglycerolipid] + 2 ferrocytochrome b5 + O2 + 2 H+ = 1-[(15Z)-tetracos-15-enoyl]-2-acyl-[phosphoglycerolipid] + 2 ferricytochrome b5 + 2 H2O
Other name(s): ADS2 (gene name)
Systematic name: very-long-chain acyl-[glycerolipid],ferrocytochrome b5:oxygen oxidoreductase (ω98-cis-dehydrogenating)
Comments: The enzyme, characterized from the plant Arabidopsis thaliana, acts on both 24:0 and 26:0 fatty acids, introducing a cis double bond at a position 9 carbons from the methyl end. These very-long-chain fatty acids are found as a minor component of seed lipids, but also in the membrane phosphatidylethanolamine and phosphatidylserine, in sphingolipids, as precursors and components of cuticular and epicuticular waxes, and in suberin.
References:
1.  Fukuchi-Mizutani, M., Tasaka, Y., Tanaka, Y., Ashikari, T., Kusumi, T. and Murata, N. Characterization of δA9 acyl-lipid desaturase homologues from Arabidopsis thaliana. Plant Cell Physiol. 39 (1998) 247–253. [PMID: 9559566]
2.  Smith, M.A., Dauk, M., Ramadan, H., Yang, H., Seamons, L.E., Haslam, R.P., Beaudoin, F., Ramirez-Erosa, I. and Forseille, L. Involvement of Arabidopsis acyl-coenzyme A desaturase-like2 (At2g31360) in the biosynthesis of the very-long-chain monounsaturated fatty acid components of membrane lipids. Plant Physiol. 161 (2013) 81–96. [PMID: 23175755]
[EC 1.14.19.75 created 2018]