ID   1.14.19.29
DE   sphingolipid 8-(E/Z)-desaturase.
AN   8 fatty acid desaturase.
AN   8-sphingolipid desaturase.
CA   (1) an N-acyl-(4R)-4-hydroxysphinganine + 2 Fe(II)-[cytochrome b5] +
CA   2 H(+) + O2 = a (4R,8E)-4-hydroxysphingenine ceramide + 2 Fe(III)-
CA   [cytochrome b5] + 2 H2O.
CA   (2) an N-acyl-(4R)-4-hydroxysphinganine + 2 Fe(II)-[cytochrome b5] +
CA   2 H(+) + O2 = (4R,8Z)-4-hydroxysphing-8-enine ceramide + 2 Fe(III)-
CA   [cytochrome b5] + 2 H2O.
CC   -!- The enzymes from higher plants convert sphinganine, 4E-sphing-4-enine
CC       and phytosphinganine into E/Z-mixtures of Delta(8)-desaturated
CC       products displaying different proportions of geometrical isomers
CC       depending on plant species.
CC   -!- The nature of the actual desaturase substrate has not yet been
CC       studied experimentally.
CC   -!- The enzymes contain an N-terminal cytochrome b5 domain that acts as
CC       the direct electron donor to the active site of the desaturase.
CC   -!- The homologous enzymes from some yeasts and diatoms, EC 1.14.19.18,
CC       act on sphing-4-enine ceramides and produce only the trans isomer.
DR   Q9ZRP7, SLD1_ARATH ;  Q9FR82, SLD1_BOROF ;  Q43469, SLD1_HELAN ;
DR   Q3EBF7, SLD2_ARATH ;
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