Reaction: a (4E,8E)-sphinga-4,8-dienine ceramide + 2 ferrocytochrome b5 + O2 + 2 H+ = a (4E,8E,10E)-sphinga-4,8,10-trienine ceramide + 2 ferricytochrome b5 + 2 H2O
Other name(s): desA (gene name)
Systematic name: a (4E,8E)-sphinga-4,8-dienine ceramide,ferrocytochrome b5:oxygen oxidoreductase (10,11 trans-dehydrogenating)
Comments: The enzyme, characterized from the marine diatom Thalassiosira pseudonana, produces an all-trans product. Similar triunsaturated sphingoid bases are found in some marine invertebrates. The enzyme determines the position of the double bond by its distance from the alcohol end of the sphingoid base, and contains a cytochrome b5 domain that acts as the direct electron donor to the active site of the desaturase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
1. Michaelson, L.V., Markham, J.E., Zäuner, S., Matsumoto, M., Chen, M., Cahoon, E.B. and Napier, J.A. Identification of a cytochrome b5-fusion desaturase responsible for the synthesis of triunsaturated sphingolipid long chain bases in the marine diatom Thalassiosira pseudonana. Phytochemistry 90 (2013) 50-55. [PMID: 23510654]