Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 26, 2007
Publication Date: July 1, 2007
Citation: Piazza, G.J., Marmer, W.N. 2007. Conversion of Phosphatidylcholine to Posphatidylglycerol with phospholipase D and Glycerol. Journal of the American Oil Chemists' Society. 84(7):645-651. Interpretive Summary: Biodiesel is manufactured from fats and oils. A coproduct of biodiesel production is glycerol. The recent expansion of biodiesel production facilities has led to a world-wide increase in glycerol, and means to use this glycerol for new products are now being sought. We investigated the use of an enzyme called phospholipase D to produce a lubricant from glycerol and lecithin, a waste product of soybean oil production. The lubricant has medical uses and may have industrial uses, too. Various commercial types of phospholipase D were tested, as well as different reaction conditions to find the best ways to synthesize the lubricant. Using a new method to follow the production of lubricant, it was found that very high levels of the lubricant could be obtained by using one commercial preparation of phospholipase D. This research will help to promote new uses both for glycerol and lecithin, and thus increasing the economic viability of producing materials from natural fats and oils.
Technical Abstract: Phosphatidylglycerol (PtdGly) is a relatively rare phospholipid that is useful in lubricant applications. Recently glycerol has become available in large quantities as a byproduct of biodiesel production, allowing for the economical synthesis of PtdGly. The conversion of readily available phosphatidylcholine to phosphatidic acid (PtdOH) and PtdGly is catalyzed by phospholipase D (PLD). A new HPLC method for following this conversion was devised. The method uses a commercial HPLC column containing a polyvinyl alcohol bonded to silica as a stationary phase. The method is compatible with evaporative light scattering detection and HPLC-MS. The column is rapidly regenerated between runs. Loss of fatty acyl groups from ester hydrolysis by contaminating lipases or phospholipases can also be detected. The utility of this method was demonstrated by finding conditions for synthesizing high levels of PtdGly using commercial PLD preparations. PLD preparations from Streptomyces chromofuscus, Streptomyces sp., and cabbage were examined in a two phase aqueous-organic solvent system. Factors examined were pH, glycerol concentration, and the type of organic solvent. It was found that PLD from Streptomyces sp. was the best catalyst, giving high PtdGly yields with a relatively low amount of glycerol. When the glycerol concentration was very low, the level of PtdOH increased, and a new species of phospholipid was detected. It is composed of the addition of two acylated phosphoglycerols on a single glycerol molecule, as determined by HPLC-MS. During the entire investigation a single HPLC column was used. The column showed no degeneration, and retention times were highly reproducible from run to run and stable over time. The method could be used for routine PLD assays and to optimize the synthesis of phospholipids by PLD.