O-alkyl lipid synthesis: the mechanism of the acyl dihydroxyacetone phosphate fatty acid exchange reaction.

We have previously provided evidence for a mechanism by which acyl DHAP is converted enzymatically to O-alkyl DHAP. This mechanism involves, in part, the formation of an endiol of acyl DHAP, loss of the fatty acid by splitting of the DHAP carbon-1 to oxygen bond and the gain of a long chain fatty alcohol. It has been shown that acyl DHAP can exchange its fatty acid for one in the medium, presumably by the mediation of O-alkyl DHAP synthase. In the present investigation we have shown that the fatty acid which is gained by acyl DHAP in the exchange process retains both carboxyl oxygens, as predicted by our postulated mechanism. This reaction is exceptional because the usual action of acyl hydrolases is to cleave at the oxygen to acyl bond.