Reaction: (1) (8Z,11Z,14Z)-icosa-8,11,14-trienoyl-CoA + 2 ferrocytochrome b5 + O2 + 2 H+ = arachidonoyl-CoA + 2 ferricytochrome b5 + 2 H2O
(2) (8Z,11Z,14Z,17Z)-icosa-8,11,14,17-tetraenoyl-CoA + 2 ferrocytochrome b5 + O2 + 2 H+ = (5Z,8Z,11Z,14Z,17Z)-icosa-5,8,11,14,17-pentaenoyl-CoA + 2 ferricytochrome b5 + 2 H2O
Other name(s): FADS1 (gene name); acyl-CoA 5-desaturase (methylene-interrupted)
Systematic name: Δ8-acyl-CoA,ferrocytochrome b5:oxygen oxidoreductase (5,6-cis-dehydrogenating)
Comments: The enzyme introduces a cis double bond at carbon 5 of acyl-CoAs that contain a double bond at position 8. The enzymes from algae, mosses, mammals and the protozoan Leishmania major catalyse the desaturation of dihomo-γ-linoleate [(8Z,11Z,14Z)-icosa-8,11,14-trienoate] and (8Z,11Z,14Z,17Z)-icosa-8,11,14,17-tetraenoate to generate arachidonate and (5Z,8Z,11Z,14Z,17Z)-icosa-5,8,11,14,17-pentaenoate, respectively. The enzyme contains a cytochrome b5 domain that acts as the direct electron donor to the desaturase active site and does not require an external cytochrome. cf. EC 1.14.19.37, acyl-CoA 5-desaturase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Cho, H.P., Nakamura, M. and Clarke, S.D. Cloning, expression, and fatty acid regulation of the human Δ5 desaturase. J. Biol. Chem. 274 (1999) 37335-37339. [PMID: 10601301]
2. Leonard, A.E., Kelder, B., Bobik, E.G., Chuang, L.T., Parker-Barnes, J.M., Thurmond, J.M., Kroeger, P.E., Kopchick, J.J., Huang, Y.S. and Mukerji, P. cDNA cloning and characterization of human Δ5-desaturase involved in the biosynthesis of arachidonic acid. Biochem. J. 347 Pt 3 (2000) 719-724. [PMID: 10769175]
3. Tripodi, K.E., Buttigliero, L.V., Altabe, S.G. and Uttaro, A.D. Functional characterization of front-end desaturases from trypanosomatids depicts the first polyunsaturated fatty acid biosynthetic pathway from a parasitic protozoan. FEBS J. 273 (2006) 271-280. [PMID: 16403015]
4. Tavares, S., Grotkjær, T., Obsen, T., Haslam, R.P., Napier, J.A. and Gunnarsson, N. Metabolic engineering of Saccharomyces cerevisiae for production of eicosapentaenoic acid, using a novel Δ5-desaturase from Paramecium tetraurelia. Appl. Environ. Microbiol. 77 (2011) 1854-1861. [PMID: 21193673]