IUBMB Enzyme Nomenclature


Accepted name: acyl-lipid (9-3)-desaturase

Reaction: (1) an α-linolenoyl-[glycerolipid] + 2 ferrocytochrome b5 + O2 + 2 H+ = a stearidonoyl-[glycerolipid] + 2 ferricytochrome b5 + 2 H2O
(2) a linoleoyl-[glycerolipid] + 2 ferrocytochrome b5 + O2 + 2 H+ = a γ-linolenoyl-[glycerolipid] + 2 ferricytochrome b5 + 2 H2O

Glossary: stearidonic acid = (6Z,9Z,12Z,15Z)-octadeca-6,9,12,15-tetraenoic acid

Other name(s): DES6 (gene name); acyl-lipid 6-desaturase; acyl-lipid Δ6-desaturase; Δ6-desaturase (ambiguous)

Systematic name: Δ9 acyl-[glycerolipid],ferrocytochrome b5:oxygen oxidoreductase (6,7-cis-dehydrogenating)

Comments: The enzyme, characterized from the moss Physcomitrella patens and the plant Borago officinalis (borage), introduces a cis double bond at carbon 6 of several acyl-lipids that contain an existing Δ9 cis double bond. The enzyme contains a cytochrome b5 domain that acts as the electron donor for the active site of the desaturase.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:


1. Sayanova, O., Smith, M.A., Lapinskas, P., Stobart, A.K., Dobson, G., Christie, W.W., Shewry, P.R. and Napier, J.A. Expression of a borage desaturase cDNA containing an N-terminal cytochrome b5 domain results in the accumulation of high levels of Δ6-desaturated fatty acids in transgenic tobacco. Proc. Natl. Acad. Sci. USA 94 (1997) 4211-4216. [PMID: 9108131]

2. Girke, T., Schmidt, H., Zähringer, U., Reski, R. and Heinz, E. Identification of a novel Δ6-acyl-group desaturase by targeted gene disruption in Physcomitrella patens. Plant J. 15 (1998) 39-48. [PMID: 9744093]

[EC created 2015]

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