Food Lipids: Chemistry, Nutrition, and Biotechnology

Moreover, transesterification, such as alcoholysis of a phospholipid with an
alcohol, such as ethanol, isopropanol, or n-butanol, catalyzed by an sn-1,3-specific
lipase from Rhizomucor miehei, has been employed for the preparation of lysophospholipids
(Fig. 41) (313).
2. Phospholipids Modified by Phospholipase D
The following examples show the various possibilities of modifying the composition
of polar head groups of phospholipids by phospholipase D–catalyzed reactions.
Such modified phospholipids may find interesting biomedical applications.
Transphosphatidylation (base exchange) reactions of phospholipids, catalyzed
by phospholipase D (Fig. 38), can be utilized for the preparation of specific phospholipids.
For example, phospholipase D–catalyzed transphosphatidylation reaction
of egg lecithin (predominantly phosphatidylcholines and phosphatidylethanolamines)
with glycerol yields phosphatidylglycerols with the simultaneous formation
of choline and ethanolamine (Fig. 42) (314,315).
Phosphatidylglycerols may find biomedical applications as physiologically active
pulmonary surfactant (316). Efficient methods have been described for the preparation
of phosphatidylglycerols from phosphatidylcholines and glycerol by transphosphatidylation
catalyzed by phospholipase D (317–319). Transphosphatidylation
reactions catalyzed by phospholipase D have also been carried out to convert ethanolamine
plasmalogens to their dimethylethanolamine or choline analogs (320) and
to obtain phosphatidylethanolamines (321) or phosphatidylserines (322,323) from
phosphatidylcholines (Fig. 43).
Phosphatidylcholine content of commercial lecithins has been increased by
transphosphatidylation of lecithins with choline chloride catalyzed by phospholipase
D (324).
Another example of phospholipase D–catalyzed transphosphatidylation reaction
is the synthesis of structural analogs of platelet-activating factor, PAF (1-Oalkyl-2-acetyl-sn-glycero-3-phosphocholine)
by the replacement of choline by primary
cyclic alcohols (325). Moreover, transphosphatidylation of pure glycerophospholipids
or commercial products, e.g., soy lecithin or egg lecithin, with a sugar,
such as glucose, using phospholipase D from an Actinomadura sp. as biocatalyst and
diethyl ether or tert-butanol as solvent affords the phosphatidylglucose or other phosphatidylsaccharides
in yields as high as 85% (Fig. 44) (326).
Transphosphatidylation of phosphatidylcholine with 1-monolauroyl-rac-glycerol,
catalyzed by phospholipase D from Streptomyces sp. yields 1-lauroyl-phosphatidylglycerol
which has been subsequently cleaved by phospholipase C from Bacillus
cereus to yield 1-lauroyl-rac-glycerophosphate (327). Similarly, transphosphatidylation
of phosphatidylcholine with 1-lauroyl-dihydroxyacetone, catalyzed by phospholipase
D, yields 1-lauroyl-phosphatidyldihydroxyacetone, which has been subsequently
cleaved by phospholipase C to yield 1-lauroyl-dihydroxyacetonephosphate
(327).
C. Other Enzymes
1. Lipoxygenases
Lipoxygenase from soybean converts linoleic acid or other compounds having a
cis,cis-1,4-pentadiene system to conjugated hydroperoxides (Fig. 45) (328). Soybean
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