Molecular properties of the oleoyl-phosphatidylcholine desaturase from Arachis hypogaea L.

Deficiencies in the activity of the microsomal oleoyl phosphatidylcholine ( oleoyl-PC) desaturase from peanuts are the basis of the high oleate oil. Mu tation of aspartate-150 to asparagine and the attendant decrease in activit y, together with the loss in expression of the higher activity transcript, was the molecular basis of the high oleate trait. The ability of oleoyl-PC desaturase to desaturate palmitoleate, oleate and 10(Z) nonadecenoate to me thylene-interrupted products was not consistent with description of this ac tivity as a Delta (12) or omega -6 desaturase. Electrospray MS was used to examine the intact phospholipid products of desaturation by the oleoyl-PC d esaturase. PC and phosphatidylinositol containing unsaturated moieties coul d be desaturated. The enzyme can act on either sn-1 or sn-2 moieties. Phosp hatidylethanolamine was a poor substrate.