Reaction: (1) an oleoyl-[glycerolipid] + 2 ferrocytochrome b5 + O2 + 2 H+ = a (9Z,12E)-octadeca-9,12-dienoyl-[glycerolipid] + 2 ferricytochrome b5 + 2 H2O
(2) a palmitoleoyl-[glycerolipid] + 2 ferrocytochrome b5 + O2 + 2 H+ = a (9Z,12E)-hexadeca-9,12-dienoyl-[glycerolipid] + 2 ferricytochrome b5 + 2 H2O
Other name(s): acyl-lipid 12-(E)-desaturase; DsFAD2-1; FADX
Systematic name: Δ9 acyl-lipid,ferrocytochrome b5:oxygen oxidoreductase (12,13 trans-dehydrogenating)
Comments: The enzymes from the plants Dimorphotheca sinuata (African daisy) and Vernicia fordii (tung oil tree) insert a trans double bond in position C-12 of oleate and palmitoleate incorporated into glycerolipids. The enzyme introduces the new double bond at a position three carbons away from an existing double bond at position 9, towards the methyl end of the fatty acid. The enzyme from tung oil tree also possesses the activity of EC 1.14.19.33, Δ12 acyl-lipid conjugase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Dyer, J.M., Chapital, D.C., Kuan, J.C., Mullen, R.T., Turner, C., McKeon, T.A. and Pepperman, A.B. Molecular analysis of a bifunctional fatty acid conjugase/desaturase from tung. Implications for the evolution of plant fatty acid diversity. Plant Physiol. 130 (2002) 2027-2038. [PMID: 12481086]
2. Cahoon, E.B. and Kinney, A.J. Dimorphecolic acid is synthesized by the coordinate activities of two divergent Δ12-oleic acid desaturases. J. Biol. Chem. 279 (2004) 12495-12502. [PMID: 14718523]