The enzyme, characterized from the endosperm of the plant Thunbergia alata (black-eyed Susan vine), introduces a cis double bond at carbon 6 of several saturated acyl-[acp]s. It is most active with palmitoyl-[acp] (16:0), but can also act on myristoyl-[acp] (14:0) and stearoyl-[acp] (18:0). The position of the double bond is determined by its distance from the carboxyl end of the fatty acid.
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The enzyme appears in viruses and cellular organisms
The enzyme, characterized from the endosperm of the plant Thunbergia alata (black-eyed Susan vine), introduces a cis double bond at carbon 6 of several saturated acyl-[acp]s. It is most active with palmitoyl-[acp] (16:0), but can also act on myristoyl-[acp] (14:0) and stearoyl-[acp] (18:0). The position of the double bond is determined by its distance from the carboxyl end of the fatty acid.
no desaturation activity with palmitoyl-CoA. DELTA6 desaturase activity is approximately 7-fold higher using palmitoyl-[acyl-carrier protein] as substrate rather than either myristoyl-[acyl-carrier protein] or stearoyl-[acyl-carrier protein]
Km-values determined for the wild-type enzyme and mutant A188G/Y189F are in the range of 0.2 to 0.6 mM with both 16:0- and 18:0-[acyl-carrier protein], suggesting that, at least in the case of these enzymes, changes in the substrate binding properties can be discounted as an underlying cause of differences in activities
the mutation yields an enzyme that functions primarily as a DELTA9-18:0-[acyl-carrier protein] desaturase. This enzyme displays only DELTA9 desaturase activity with 18:0-[acyl-carrier protein] and is nearly 4-fold more active with this substrate than with 16:0-[acyl-carrier protein]. Like mutant A181TyA200F, this enzyme retains DELTA6 desaturase activity with 16:0-[acyl-carrier protein]
the mutation gives rise to an enzyme that catalyzed primarily the DELTA9 desaturation of 18:0-[acyl-carrier protein], but functions as a DELTA6 desaturase with 16:0-[acyl-carrier protein]
replacement of specific amino acid residues in a DELTA6-palmitoyl (16:0)-[acyl-carrier protein] desaturase with their equivalents from a DELTA9-stearoyl (18:0)-[acyl-carrier protein] desaturase. The A181T/A200F/S205N/L206T/G207A mutant enzyme is functions principally as a DELTA9-18:0-[acyl-carrier protein] desaturase
replacement of specific amino acid residues in a DELTA6-palmitoyl (16:0)-[acyl-carrier protein] desaturase with their equivalents from a DELTA9-stearoyl (18:0)-[acyl-carrier protein] desaturase, mutant enzymes are identified that have altered fatty acid chain-length specificities or that can insert double bonds into either the DELTA6 or DELTA9 positions of 16:0- and 18:0-[acyl-carrier protein]