Study of the partially purified C18:1-CoA elongase from developing rapeseeds (Brassica napus L.)

Abstract

Erucic acid is the main constituent of the triacylglycerol from rapeseed oil, it results from the elongation of oleoyl-CoA by malonyl-CoA (1). The acyl-CoA elongase, the enzyme responsible for the erucic acid synthesis, is mainly located in the ER (2). Since these intermediates have been evidenced in L. annua (3). these results supporte that the elongation process could involve the following reactions : i) condensation leading to the formation of a 3-keto acyl-CoA, ii) reduction of the keto acyl-CoA into a 3-OH acyl-CoA, iii) dehydratation of the 3-OH acyl-CoA and, finally, reduction of the trans 2–3 enoyl-CoA. Nevertheless, the organization, the structure and the different reactions involved in the elongation process remain largely unknown. This is due for a large part to the difficulties encountered during the purification of the membrane-bound enzymes. The solubilization of acyl-CoA elongases from oil seeds has been reported (4,5), and only one purification has been attempted leading to the obtention of a partially purified enzyme (4).