Oxidoreductases;
Acting on paired donors, with incorporation or reduction of molecular oxygen;
With oxidation of a pair of donors resulting in the reduction of O2 to two molecules of water
BRITE hierarchy

(4E)-sphing-4-enine ceramide,ferrocytochrome b5:oxygen oxidoreductase (8,9-trans dehydrogenating)

a (4E)-sphing-4-enine ceramide + 2 ferrocytochrome b5 + O2 + 2 H+ = a (4E,8E)-sphing-4,8-dienine ceramide + 2 ferricytochrome b5 + 2 H2O [RN:R11005]

R11005
Reaction

(4E)-sphing-4-enine ceramide [CPD:C00195];
ferrocytochrome b5 [CPD:C00999];
O2 [CPD:C00007];
H+ [CPD:C00080]

The enzyme, characterized from the yeasts Kluyveromyces lactis and Candida albicans [1] and from the diatom Thalassiosira pseudonana [2], introduces a trans double bond at the 8-position of sphingoid bases in sphingolipids. 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 [3]. The homologous enzymes from higher plants, EC 1.14.19.29, sphingolipid 8-(E/Z)-desaturase, act on phytosphinganine (4-hydroxysphinganine) and produces a mixture of trans and cis isomers.

EC 1.14.19.18 created 2015

1  [PMID:12402089]

2  [PMID:15978045]

3  [PMID:19047747]