The Enzyme Database

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EC 1.14.19.29     
Accepted name: sphingolipid 8-(E/Z)-desaturase
Reaction: (1) a (4R)-4-hydroxysphinganine ceramide + 2 ferrocytochrome b5 + O2 + 2 H+ = a (4R,8E)-4-hydroxysphing-8-enine ceramide + 2 ferricytochrome b5 + 2 H2O
(2) a (4R)-4-hydroxysphinganine ceramide + 2 ferrocytochrome b5 + O2 + 2 H+ = a (4R,8Z)-4-hydroxysphing-8-enine ceramide + 2 ferricytochrome b5 + 2 H2O
Glossary: a (4R)-4-hydroxysphinganine-ceramide = a phytoceramide
(4R)-4-hydroxysphinganine = phytosphinganine
Other name(s): 8-sphingolipid desaturase (ambiguous); 8 fatty acid desaturase (ambiguous); DELTA8-sphingolipid desaturase (ambiguous)
Systematic name: (4R)-4-hydroxysphinganine ceramide,ferrocytochrome b5:oxygen oxidoreductase (8,9 cis/trans-dehydrogenating)
Comments: The enzymes from higher plants convert sphinganine, 4E-sphing-4-enine and phytosphinganine into E/Z-mixtures of Δ8-desaturated products displaying different proportions of geometrical isomers depending on plant species. The nature of the actual desaturase substrate has not yet been studied experimentally. The enzymes contain an N-terminal cytochrome b5 domain that acts as the direct electron donor to the active site of the desaturase [1]. The homologous enzymes from some yeasts and diatoms, EC 1.14.19.18, sphingolipid 8-(E)-desaturase, act on sphing-4-enine ceramides and produce only the trans isomer.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Sperling, P., Zähringer, U. and Heinz, E. A sphingolipid desaturase from higher plants. Identification of a new cytochrome b5 fusion protein. J. Biol. Chem. 273 (1998) 28590–28596. [PMID: 9786850]
2.  Sperling, P., Blume, A., Zähringer, U., and Heinz, E. Further characterization of Δ8-sphingolipid desaturases from higher plants. Biochem Soc Trans. 28 (2000) 638–641.
3.  Sperling, P., Libisch, B., Zähringer, U., Napier, J.A. and Heinz, E. Functional identification of a Δ8-sphingolipid desaturase from Borago officinalis. Arch. Biochem. Biophys. 388 (2001) 293–298. [PMID: 11368168]
4.  Beckmann, C., Rattke, J., Oldham, N.J., Sperling, P., Heinz, E. and Boland, W. Characterization of a Δ8-sphingolipid desaturase from higher plants: a stereochemical and mechanistic study on the origin of E,Z isomers. Angew. Chem. Int. Ed. Engl. 41 (2002) 2298–2300. [PMID: 12203571]
5.  Ryan, P.R., Liu, Q., Sperling, P., Dong, B., Franke, S. and Delhaize, E. A higher plant Δ8 sphingolipid desaturase with a preference for (Z)-isomer formation confers aluminum tolerance to yeast and plants. Plant Physiol. 144 (2007) 1968–1977. [PMID: 17600137]
6.  Chen, M., Markham, J.E. and Cahoon, E.B. Sphingolipid Δ8 unsaturation is important for glucosylceramide biosynthesis and low-temperature performance in Arabidopsis. Plant J. 69 (2012) 769–781. [PMID: 22023480]
[EC 1.14.19.29 created 2015]
 
 


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