Accepted name: palmitoyl-[glycerolipid] 3-(E)-desaturase
Reaction: a 1-acyl-2-palmitoyl-[glycerolipid] + 2 reduced ferredoxin [iron-sulfur] cluster + O2 + 2 H+ = a 1-acyl-2-[(3E)-hexadec-3-enoyl]-[glycerolipid] + 2 oxidized ferredoxin [iron-sulfur] cluster + 2 H2O
Other name(s): FAD4
Systematic name: 1-acyl-2-palmitoyl-[glycerolipid],ferredoxin:oxygen oxidoreductase (3,4-trans -dehydrogenating)
Comments: The enzyme introduces an unusual trans double bond at carbon 3 of a palmitoyl group attached to the sn-2 position of glycerolipids. The enzyme from the plant Arabidopsis thaliana is specific for palmitate in phosphatidylglycerol. The enzyme from tobacco can also accept oleate and α-linolenate if present at the sn-2 position of phosphatidylglycerol [1].
1.  Fritz, M., Lokstein, H., Hackenberg, D., Welti, R., Roth, M., Zähringer, U., Fulda, M., Hellmeyer, W., Ott, C., Wolter, F.P. and Heinz, E. Channeling of eukaryotic diacylglycerol into the biosynthesis of plastidial phosphatidylglycerol. J. Biol. Chem. 282 (2007) 4613–4625. [PMID: 17158889]
2.  Gao, J., Ajjawi, I., Manoli, A., Sawin, A., Xu, C., Froehlich, J.E., Last, R.L. and Benning, C. FATTY ACID DESATURASE4 of Arabidopsis encodes a protein distinct from characterized fatty acid desaturases. Plant J. 60 (2009) 832–839. [PMID: 19682287]
[EC created 2015]