In search of a phospholipin precursor

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Abstract
It has been shown that the specific activity-time curve of the ethanol-precipitable P, obtained from the acid-soluble phosphates of liver, fulfills the criteria for this fraction being the P precursor of lecithin and cephalin. This acid-soluble P fraction, labelled with P32, was identified by crystallization as consisting mainly of alpha- and beta-glycerophosphate. Lecithin and cephalin labelled with p32 were injd. into rabbits. The glycero-phosphate from placenta and liver had the highest specific activity after the phospholipins. The results were considered to indicate that glycerophosphate is the P precursor of phospholipins and that the reaction is reversible. Although neither in vivo nor in vitro expts. with p32-labelled glycerophosphate provided supporting evidence for the above thesis, the negative results were attributed to failure of penetration of liver cells by glycerophosphate. The turnover time of phospholipins in the rat liver was calculated to be 6.75 hrs. Possible mechanisms for the biochemical synthesis of lecithin and cephalin were discussed.