Enzymatic Synthesis of Structured Phospholipids

Phospholipids are a major component of all cell membranes. They are amphiphilic and can form a variety of structures which find applications in nanotechnology and materials science. Deuterated analogues are useful for neutron experiments and have been used to investigate drug-membrane interactions, for instance. However, deuterated analogues of these molecules generally contain two of the same acyl chain (homo-acyl), when in reality they most often contain different acyl chains (hetero-acyl) (Figure 1). This is because synthesis of phospholipids containing different chains, using standard chemical techniques, is much more challenging than the synthesis of phospholipids containing the same chain.

POPC-h and DPPC-h with  names.png
POPC, a hetero-acyl phospholipid, and DPPC, a homo-acyl phospholipid.

At ESS, we proposed using enzymes in the preparation of hetero-acyl phospholipids, because of the remarkable regioselectivity they display. Beginning with a homo-acyl phospholipid (DOPC), we planned that we could hydrolyse a single chain, specifically, using either porcine pancreas phospholipase A2 or Rhizomucor miehei lipase, and then esterify using deuterated acid anhydrides (Scheme 1):

POPC-d64 synthesis
Proposed synthesis of chain-deuterated, hetero-acyl phospholipids in four steps.

Inital work towards POPC-d64 is promising and this molecule was offered in the first round of the ESS Deuteration and Macromolecular Crystallisation (DEMAX) Platform’s call for proposals. Future work will focus on producing chain-deuterated oxidised lipids and perdeuterated lipids.