Desaturation of Oleyl Phospholipid to Linoleyl Phospholipid in Torulopsis utilis

An enzyme system from Torulopsis utilis consisting of microsomal pellet and supernatant (100,000 x g) catalyzes the conversion of either oleyl-CoA or oleyl phospholipid to linoleate. The desaturation of oleyl phospholipid has been demonstrated both with biosynthetic and chemically synthesized substrate. Incubation of Torulopsis particles with [3H]-oleyl-CoA in the absence of supernatant affords [3H]-oleyl phospholipid. This material is desaturated to linoleate either in situ after addition of supernatant or, after isolation, by the complete enzyme system. Fractionation of the biosynthetic [3H]oleyl lipid indicates that oleyl phosphatidylcholine is the most active of the various phospholipid fractions for desaturation. Synthetic 1,2-di[14C]oleyl phosphatidylcholine is converted to linoleate with high efficiency. Linoleate formation from either biosynthetic or chemically synthesized oleyl phospholipid requires both the particulate fraction and the supernatant from Torulopsis extracts.