Preparation of Phosphatidylserine from Soybean Phospholipid by Cabbage Phospholipase D

We have tried to prepare phosphatidylserine (PS) using phosphatidylcholine (PC) concentrated soybean phospholipid (PC-90) which was composed of 90% PC and 10% phosphatidylethanolamine (PE), and serine by the transphosphatidylation with phospholipase D from fresh cabbage leaves. The optimum conditions for PS preparation were determined as follow : PC-90, 0.13mmol; diethylether, 5mL; acetate buffer (pH 6.5) which contained 1M CaCl2, 3mL; phospholipase D from fresh cabbage leaves, 0.5IU. The conversion ratio from PC-90 to PS reached to 37% for 2h under the optimum condition PC, a main component of the substrate, decreased remarkably by the transphosphatidylation or the hydrolysis, but a small amount of PE was converted into PS.Transphosphatidylation activity of the enzyme was much enhanced by pre-incubation with acetate buffer at pH 5.6 for 1h. The conversion ratio from PC-90 to PS with the pre-incubated enzyme reached to 52% after 30min under the optimum condition.