Phospholipase D-Catalyzed Transphosphatidylation for the Synthesis of Rare Complex Phospholipid Species─Hemi-bis(monoacylglycero)phosphate and Bis(diacylglycero)phosphate

Progress in developing synthetic pathways for novel and complex phospholipid species, such as Hemi-bis(monoacylglycero)phosphates (Hemi-BMPs) and bis(diacylglycero)phosphates (BDPs), is essential for expanding the knowledge and availability of rare and uncommon phospholipid species. These structurally complex phospholipid species have recently gained more attention with promising applications, as active pharmaceutical ingredient carriers in multiple COVID-19 vaccines, or biomarkers for numerous lysosomal storage disorders and certain types of cancers. The presented work facilitates the production of a range of structurally diverse Hemi-BMP and BDP products intending to increase the availability and thereby the understanding of the underlying chemistry for these high-valuable compounds. The transphosphatidylation of phosphatidylcholine with a variety of structurally diverse monoacylglycerols and diacylglycerols is proceeded by phospholipase D (PLD) catalysis in a biphasic system. Optimization in regard to enzyme loading (5 U), substrate mole ratio (1:5 mol/mol), temperature (30 °C), and aqueous concentration of (18% v/v) afforded the highest conversion for the model transphosphatidylation of phosphatidylcholine with monoolein, yielding 87% in 2 h. The study additionally proposes a reaction mechanism based on molecular simulation, elegantly elaborating the structural constraints (substrate configuration and character of the fatty acid residues) for access to the active site of PLD accordingly for lower yield of BDPs. The successful system designed for the production of high-valuable Hemi-BMP and BDP-analogues demonstrated in this work promises to enhance the understanding of these complex phospholipids, leading to new scientific breakthroughs.