Reaction: an oleoyl-[glycerolipid] + 2 ferrocytochrome b5 + O2 + 2 H+ = a linoleoyl-[glycerolipid] + 2 ferricytochrome b5 + 2 H2O
Other name(s): oleate desaturase (ambiguous); linoleate synthase (ambiguous); oleoyl-CoA desaturase (incorrect); oleoylphosphatidylcholine desaturase (ambiguous); phosphatidylcholine desaturase (ambiguous); n-6 desaturase (ambiguous); FAD2 (gene name)
Systematic name: 1-acyl-2-oleoyl-sn-glycero-3-phosphocholine,ferrocytochrome-b5:oxygen oxidoreductase (12,13 cis-dehydrogenating)
Comments: This microsomal enzyme introduces a cis double bond in fatty acids attached to lipid molecules at a location 6 carbons away from the methyl end of the fatty acid. The distance from the carboxylic acid end of the molecule does not affect the location of the new double bond. The most common substrates are oleoyl groups attached to either the sn-1 or sn-2 position of the glycerol backbone in phosphatidylcholine. cf. EC 1.14.19.23, acyl-lipid ω-6 desaturase (ferredoxin).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Pugh, E.L. and Kates, M. Characterization of a membrane-bound phospholipid desaturase system of Candida lipolytica. Biochim. Biophys. Acta 380 (1975) 442-453. [PMID: 166662]
2. Slack, C.R., Roughan, P.G. and Browse, J. Evidence for an oleoyl phosphatidylcholine desaturase in microsomal preparations from cotyledons of safflower (Carthamus tinctorius) seed. Biochem. J. 179 (1979) 649-656. [PMID: 475773]
3. Stymne, S. and Appelqvist, L.-A. The biosynthesis of linoleate from oleoyl-CoA via oleoyl-phosphatidylcholine in microsomes of developing safflower seeds. Eur. J. Biochem. 90 (1978) 223-229. [PMID: 710426]
4. Smith, M.A., Cross, A.R., Jones, O.T., Griffiths, W.T., Stymne, S. and Stobart, K. Electron-transport components of the 1-acyl-2-oleoyl-sn-glycero-3-phosphocholine Δ12-desaturase (Δ12-desaturase) in microsomal preparations from developing safflower (Carthamus tinctorius L.) cotyledons. Biochem. J. 272 (1990) 23-29. [PMID: 2264826]
5. Kearns, E.V., Hugly, S. and Somerville, C.R. The role of cytochrome b5 in Δ12 desaturation of oleic acid by microsomes of safflower (Carthamus tinctorius L.). Arch. Biochem. Biophys. 284 (1991) 431-436. [PMID: 1989527]
6. Miquel, M. and Browse, J. Arabidopsis mutants deficient in polyunsaturated fatty acid synthesis. Biochemical and genetic characterization of a plant oleoyl-phosphatidylcholine desaturase. J. Biol. Chem. 267 (1992) 1502-1509. [PMID: 1730697]