Transphosphatidylation by immobilized phospholipase D in aqueous media

Phospholipase D (PLD) from Streptomyces sp. was immobilized by covalent binding to aminopropyl-glass activated by glutardialdehyde and to the macroporous synthetic polymer VA-Epoxy Biosynth (from Riedel-de Häen, Seelze, Germany) pre-activated by epoxy groups. The immobilized PLDs were examined for the synthesis of phosphatidylglycerol (PG) from soybean (Glycine max) phosphatidylcholine (PC) in purely aqueous solutions in comparison with commonly used diethyl ether/buffer systems. In contrast with general assumptions, the transphosphatidylation was shown to yield a high percentage of PG, even in pure buffer. With PLD immobilized to VA-Epoxy Biosynth, the formation of phosphatidic acid (PA) is insignificant, while the yield of PG amounts to 60%. With PLD immobilized to porous glass (average pore diameter 17 nm), higher yields of PG (72%) are reached, but the formation of PA also increases (up to 10%). In comparison with the reaction in the diethyl ether/buffer system, however, the conversion of PC into PG proceeds much more slowly. Detergents such as Triton X-100 accelerate the reaction.