14.9 Possibleexchangereactionsinglycerophospholipids
Reactions catalyzed by lipases and phospholipases which have reported to work
reasonably well are listed in Table 3. By using lipases, hydrolysis, esterification
and transesterification can each be carried out in thesn-1 position. The hydrolysis
reaction can give practically quantitative yields, while the esterification and trans-
esterification reactions give reasonable yields (up to about 60–70 %) if suitable
reaction conditions are used. With all the different phospholipases available, hydro-
lysis can provide essentially quantitative yields. Pancreatic phospholipase A 2 func-
tions reasonably well for esterification, but cannot catalyze transesterification. How-
ever, it has been shown possible to use this enzyme to exchange the fatty acid in the
sn-2 position in a one-step reaction. In this case, hydrolysis and re-esterification with
the new fatty acid occur in parallel.
With regard to the incorporation of new polar groups, the only reaction reported to
work well is the transphosphatidylation catalyzed by phospholipase D.
In summary, by using the three enzymes of lipase, phospholipase A 2 and phos-
pholipase D, the different regions of the glycerophospholipid molecule that one
might wish to exchange, can indeed be exchanged. Thus, it is possible – by starting
with a natural glycerophospholipid mixture–to create a tailor-made and well-defined
product.
14.10 Conclusions
Enzymes can be used to convert a natural glycerophospholipid mixture to a well-
defined product having specified fatty acids in thesn-1 andsn-2 positions, together
with a specified, natural or unnatural, polar group. The enzymes used to catalyze
these reactions include lipases, phospholipase A 2 and phospholipase D. The ex-
change reactions may often be carried out either using a two-step combination of
hydrolysis and esterification with an intermediate separation step to remove the
moiety to be replaced, or as a one-step reaction. In the latter case, an excess of
the moiety to be incorporated is required as there is a competition between this
moiety and that to be replaced.
14.11 References
Adlercreutz, P. (1994), Enzyme-catalyzed lipid modification,Biotechnol. Gen. Eng. Rev. 12 , 231–254.
Anthonsen, T., D’Arrigo, P., Pedrocchi-Fantoni, G., Secundo, F., Servi, S., Sundby, E. (1999), Phospho-
lipids hydrolysis in organic solvents catalyzed by immobilised phospholipase C,J. Mol. Catal. B:
Enzym. 6 , 125–132.
Brockerhoff, H., Schmidt, P.C., Fong, J.W., Tirri, L.J. (1976), Introduction of labeled fatty acid in position
1 of phosphoglycerides,Lipids 11 , 421–422.
Brockerhoff, H., Yurkowski, M. (1965), Simplified preparation of L-a-glycerylphosphorylcholine,Can. J.
Biochem. 43 , 1777.
Buchold, H. (1993), Enzymatische Phosphatidentfernung aus Pflanzeno ̈len,Fat. Sci. Technol. 95 , 300–
304.