Separations of soy bean inositide fractions of low partition coefficient.

The inositol-containing phosphatides of soy beans have been the subject of a number of investigations (l-7) since 1939 when Klenk and Sakai (8) first reported the presence of inositol in soy bean phosphatides. Previous work at the Northern Regional Research Laboratory (3) has shown that the alcohol-insoluble portion of soy bean phosphatides can be separated into two inositol-containing fractions by counter-current distribution between hexane and 95 per cent methanol. If free sugars have previously been removed by extracting the phosphatides with 55 per cent alcohol, then that inositol-containing fraction of lower partition coefficient (the one more soluble in methanol) is almost sugar-free (9). We have repeated this work on a larger scale with essentially the same results, which are shown graphically in Fig. 1. In the present paper we wish to report on the further fractionation of the material of lower partition coefficient in Tubes 7 through 13 (Fraction A) and in Tubes 14 through 17 (Fraction B). These fractions were chosen for further work because they are low in sugarcontaining impurities and because the nitrogen, phosphorus, and inositol contents of the tubes combined were quite comparable. In our fractionation studies we employed two methods: (1) precipitatian from chloroform solution with methanol, and (2) precipitation from methanol with lead acetate. By means of these procedures, it has been possible to separate Fractions A and B into a fraction rich in phosphatidyl ethanolamine and another rich in nitrogen-free phosphoinositides. Although inositol phosphatidic acids have been reported from other sources (lo-12), the present communication constitutes the first description of them in soy bean phosphatides. Similarly phosphatidyl ethanolamine has been prepared in comparatively pure state from brain lipides (13) and was, in fact, obtained from soy bean phosphatides in 1925 by Levene and Rolf (14) in a concentrate containing 25 per cent lecithin. However, the present isolation from the fraction of low partition coefficient by the use of lead acetate yields phosphatidyl ethanolamine in 90 to 95 per cent purity and provides a potential preparative method.