Soybean protein bodies: Phospholipids and phospholipase D activity

Protein bodies from mature soybeans were isolated by differential centrifugatioin to examine their composition and relationship with phospholipase D. Densities were adjusted by varying mixtures of soybean oil and carbon tetrachloride. The purity of the final isolate was confirmed by electron microscopy. Approximately 4.5% by weight of the protein bodies was lipid and 2.0% by weight phospholipid. Thin-layer chromatography revealed only a trace of phosphatidic acid. Treatment with 60% ethanol/40% sodium acetate buffer (pH 5.6) (vol/vol) resulted in phosphatidyl transferase activity with conversion of both phosphatidylcholine and phosphatidylethanolamine into phosphatidylethanol. It is proposed that protein bodies of soybeans contain phospholipase D.