SOYBEAN PROTEIN BODIES - PHOSPHOLIPIDS AND PHOSPHOLIPASE-D ACTIVITY

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