strates) was used as solvent. At temperatures favoring the precipitation of the mono-
acylated products, LPC, high yields were obtained. The formation of the diacylated
product, phosphatidylcholine (PC), was less favored than the formation of phospha-
tidic acid in the synthesis discussed above; this might be due to the substrate pre-
ferences of the enzymes used. Another possible reason is that acyl migration which is
a necessary step for the diacylation might have been slower in LPC than in LPA.
Free fatty acids can also be used as acyl donors in this type of reaction. A solvent-
free esterification of glycerophosphorylcholine with capric acid catalyzed by Lipo-
zyme resulted in a LPC yield of 36 % when the water activity was controlled to 0.60
by the use of a pair of salt hydrates (Han and Rhee, 1998). When glycerophosphoryl-
ethanolamine was used as substrate in a similar reaction, the optimal water activity
was 0.37 and the corresponding LPE yield was 23 % (Han and Rhee, 1998). When
lauric acid was used in theCandida antarcticalipase B-catalyzed acylation of gly-
cerophosphorylcholine, a yield of about 50 % was obtained (Virto and Adlercreutz,
2000a).
300 14 Enzymatic Conversions of Glycerophospholipids
Table 2.Phospholipase A 2 -catalyzed acylation of lysophospholipids.
Enzyme Solvent Acyl
donor
Product^1 Yield^2 Comments ReferenceNaja najavenom Toluene Oleic
acid
PC 6.5 % Pernas et al., 1990Pancreatic Microemulsion
(isooctane)
PUFA PC 6 % Na et al., 1990Pancreatic Benzene Oleic
acid
PC 35 % Mingarro et al.,
1994Pancreatic Isooctane PUFA PC 21 % Lilja-Hallberg and
Ha ̈rro ̈d, 1995
Pancreatic Propane PUFA PC 25 % High-pressure
reactor
Ha ̈rro ̈d and Elf-
man, 1995Pancreatic Glycerol PUFA PC 40 % Formamide
added as
water mimic
Hosokawa et al.,
1995bPancreatic Glycerol PUFA PE 27 % Hosokawa et al.,
1995a
Pancreatic on
XAD-8
Toluene Fatty
acidsPC 60 % Water activity
controlEgger et al., 1997(^1) PC, phosphatidylcholine; PE, phosphatidylethanolamine.
(^2) Analytical yields.
PUFA, polyunsaturated fatty acids.