Comparative study on conversion of phosphatidylcholine to phosphatidylglycerol by cabbage phospholipase D in micelle and emulsion systems

Transphosphatidylation was carried out for phosphatidylglycerol (PG) synthesis from phosphatidylcholine (PC) with the help of cabbage phospholipase D (PLD) in the presence of glycerol. Since PLD catalyses both the hydrolysis and the transfer (base exchange) reactions simultaneously, the comparative investigation was conducted between PC micelles in glycerol-buffer and emulsion of glycerol-buffer in ether containing dissolved PC to minimize formation of the byproduct phosphatidic acid (PA). Various controlling factors including glycerol concentration, substrate concentration, reversibility of end product to byproduct etc. were examined. The initial rate of PG formation was higher in the PC micelles in glycerol-buffer, but so was the proportion of byproduct PA formation. However, the emulsion of glycerol-buffer in ether containing the dissolved PC system seems to be more attractive because almost 100% conversion of PC and 100% selectivity of PG could be achieved at 30% (w/w) glycerol without any significant formation of PA, which guarantees achieving pure product and saving some of the cost of downstreaming as well as no loss of the raw material (PC).