Cyclic glycerophosphate formation from the glycerolphosphatides.

Classification and analysis of ionic lipides and glycolipides are simplified greatly when the method of Dawson (1) for deacylation is followed by paper chromatographic separation of the resultant phosphate diesters and glycosides. With radioactive lipides the radiochromatographic method provides the sensitivity and accuracy essential for studies of the metabolism of these important compounds. The glycerolphosphatides of plants are readily deacylated by 15 minutes of treatment with 0.1 nt methanolic potassium hydroxide (1, 2). It is known (3, 4), however, that extended methanolysis produces the glycerophosphates and methyl glycerophosphate. Cyclic 1,2-glycerophosphatel can be anticipated (4) as an intermediate in base-catalyzed transesterification of glycerophosphoryl esters as a result of investigations of the mechanism of nucleic acid hydrolysis (6-9). The possibility of isolating the cyclic ester was investigated by Ukita et al. (4, 5). They found that the RF values of methyl glycerophosphates and cyclic 1,2-glycerophosphate were identical but concluded that there was no evidence for accumulation of the cyclic glycerophosphate during hydrolyses of lecithin under their experimental conditions. Recent developments have clarified the hydrolysis mechanism of this type of phosphate ester as a base-catalyzed transesterification followed by alcoholysis or hydrolysis of the cyclic glycerophosphate (Fig. 1). In extending our survey of the distribution of the phosphatidyl glycerols we observed an unidentified spot in P32 radiograms which corresponded in Rg to the unidentified product reported by Dawson (1) in hydrolysates of rat liver phosphatides. This paper describes results of an investigation of this product.