This plastidial enzyme is able to insert a cis double bond in monounsaturated fatty acids incorporated into glycerolipids. The enzyme introduces the new bond at a position 3 carbons away from the existing double bond, towards the methyl end of the fatty acid. The native substrates are oleoyl (18:1 ¦¤9) and (Z)-hexadec-7-enoyl (16:1 ¦¤7) groups attached to either position of the glycerol backbone in glycerolipids, resulting in the introduction of the second double bond at positions 12 and 10, respectively This prompted the suggestion that this is an ¦Ø6 desaturase. However, when acting on palmitoleoyl groups(16:1 ¦¤9), the enzyme introduces the second double bond at position 12 (¦Ø4), indicating it is an (n+3) desaturase [3]. cf. EC 1.14.19.34, acyl-lipid (9+3)-(E)-desaturase.
