The mechanism of ether bond formation in O-alkyl lipid synthesis

O-Alkyl dihydroxyacetone phosphate is formed enzymatically from acyl dihydroxyacetone phosphate and a long chain fatty alcohol. This reaction is accompanied by stereospecific exchange of the pro-R hydrogen of carbon 1 (carbon 1 of all compounds corresponds to carbon 1 of sn-glycerol) of the dihydroxyacetone phosphate moiety with retention of configuration. In the present investigation, data are provided to show that the initial loss of hydrogen from carbon 1 of acyl dihydroxyacetone phosphate does not depend on the presence of the fatty alcohol. In addition, the occurrence of a Schiff base between enzyme and acyl dihydroxyacetone phosphate, comparable to the fructose-1,6-diphosphate aldolase reaction, could not be demonstrated. It is concluded that the formation of 1-O-alkyl dihydroxyacetone phosphate via the formation of intermediate 1-O-acyl endiol and 1-O-alkyl endiol is a likely mechanism.