under conditions which induce acyl migration, fully acylated lipids can be prepared.
As mentioned earlier, the lipase-catalyzed synthesis of phosphatidic acid from gly-
cerophosphate and of phosphatidylcholine from glycerophosphorylcholine have
been reported (Virto and Adlercreutz, 1999a; Virto et al., 1999). The corresponding
reaction catalyzed by phospholipase A 2 has not yet been reported, but it should be
possible to carry out. The acyl migration step should be more favorable in this case as
the 1-acyl-lysolipid is more stable than the 2-acyl-lysolipid. The syntheses using just
one of the enzymes and acyl migration yield products with the same fatty acid in both
positions. In order to produce glycerolipids with one specific fatty acid in thesn-1
position and another in thesn-2 position, the two enzymes should be used separately
(Figure 8).
14.6 Lipase-catalyzed transesterification reactions
Lipases are useful for the exchange of fatty acids in thesn-1 position of glyceropho-
spholipids using the one-step transesterification approach. In the earliest attempts,
the fatty acid and the phospholipid were dispersed as micelles in aqueous buffer, but
the yields were moderate (14–23 % yield with 18 % incorporation of the new fatty
acid) (Brockerhoff et al., 1976). When the diacylated glycerophospholipid is the
desired product, a main point is to limit the extent of lysophospholipid forma-
302 14 Enzymatic Conversions of Glycerophospholipids
Figure 8. Theoretically possible ways to acylate glycerophospholipids. The reactions which have been
found to work reasonably well (at least for one class of glycerophospholipids) are marked with bold
arrows, and other reactions with normal arrows. The final products are glycerophospholipids with either
the same fatty acid in both positions or with two different fatty acids introduced in a regioselective manner.
PLA 2 , phospholipase A 2.