Biosynthesis of O-acyl ethanediol phosphorylcholine in a cell-free system from rat liver.

1-$\text{0}$-Hexadecanoyl U-¹⁴C]ethanediol can serve as substrate in the formation of 1-$\text{0}$-hexadecanoyl ethanediol 2-phosphorylcholine by particulate cell-free preparations from rat liver. Catalytic activity is largely associated with the microsomal fraction. The reaction requires CDPcholine and Mg⁺⁺. Phosphatidylcholine cannot substitute for CDPcholine, but Mn⁺⁺ is almost as effective as Mg⁺⁺. Ca⁺⁺ inhibits the reaction. The acyl ethanediol phosphorylcholine produced was identified by repeated cochromotography with authentic diol phospholipid to constant specific radioactivity, and by enzymatic and chemical degradations.