- An (8Z,11Z,14Z)-icosa-8,11,14-trienoyl-[glycerolipid] + 2 ferrocytochrome b5 + O(2) + 2 H(+) <=> a (5Z,8Z,11Z,14Z)-icosatetra-5,8,11,14-tetraenoyl-[glycerolipid] + 2 ferricytochrome b5 + 2 H(2)O
- An (8Z,11Z,14Z,17Z)-icosa-8,11,14,17-tetraenoyl-[glycerolipid] + 2 ferrocytochrome b5 + O(2) + 2 H(+) <=> a (5Z,8Z,11Z,14Z,17Z)-icosa-5,8,11,14,17-pentaenoyl-[glycerolipid] + 2 ferricytochrome b5 + 2 H(2)O
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- The enzyme, which has been characterized from multiple organisms
including the moss Physcomitrella patens, the marine microalga
Rebecca salina, and the filamentous fungus Mortierella alpina,
introduces a cis double bond at the 5-position in 20-carbon
polyunsaturated fatty acids incorporated in a glycerolipid that
contain a Delta(8) double bond.
- The enzyme contains a cytochrome b5 domain that acts as the direct
electron donor to the active site of the desaturase, and does not
require an external cytochrome.
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