Lipase‐catalyzed acidolysis and phospholipase D‐catalyzed transphosphatidylation of phosphocholine

Abstract

AbstractTwo approaches on enzymatic phospholipid modification were studied: (1) transphosphatidylation of the 1,2‐dilauroyl‐sn‐glycero‐3‐phosphocholine (DLPC) and ethanolamine in biphasic and anhydrous organic solvent systems by phospholipase D (PLD) and (2) incorporation of oleic acid into the sn1‐position of DLPC in organic solvents with different immobilized lipases at controlled water activity. First, DLPC was chemically synthesized from glycerophosphocholine and lauric acid. Next, PLD‐catalyzed head group exchange of DLPC with ethanolamine was studied using an enzyme from Streptomyces antibioticus expressed recombinantly in E. coli. A comparison of the free PLD with the biocatalyst activated by a salt‐activation technique using KCl showed that the salt‐activated enzyme (PLD‐KCl) was 10–12 folds more active based on the amount of protein used. Thus, DLPC was quantitatively converted to 1,2‐dilauroyl‐sn‐glycero‐3‐phosphoethanolamine in an anhydrous solvent system within 12 h at 60 °C. For the acidolysis of DLPC with oleic acid, among the four lipases studied (CAL‐B, Lipozyme TL IM, Lipozyme RM IM and lipase D immobilized on Accurel EP‐100), Lipozyme TL IM showed the highest activity and incorporation of oleic acid. A quantitative incorporation was achieved at 40 °C using a 8‐fold molar excess of oleic acid in n‐hexane at a water activity of 0.11.