Hydrogen exchange in the formation of dihydroxyacetone phosphate from acyl dihydroxyacetone phosphate in O-alkyl lipid synthesis in Ehrlich ascites tumor cell microsomes.

We have previously presented evidence that acyl dihydroxyacetone phosphate is converted to O-alkyl dihydroxyacetone phosphate via an endiol intermediate which then accepts a fatty alcohol to form O-alkyl dihydroxyacetone phosphate. We have further proposed that, in the absence of fatty alcohol, the endiol derivative of acyl dihydroxyacetone phosphate reacts with water to form dihydroxyacetone phosphate. In support of this hypothesis, we have shown, in an O-alkyl generating system, that the amount of hydrogen released from acyl dihydroxyacetone phosphate in the formation of the endiol is greater than the amount of hydrogen lost from the total lipid present at the end of incubation. The discrepancy is greater in the absence of added hexadecanol. The balance of the hydrogen loss can be accounted for by the formation of a non-lipid substance which was identified as dihydroxyacetone phosphate.