14 Enzymatic Conversions of
Glycerophospholipids
Patrick Adlercreutz
14.1 Introduction
Glycerophospholipids, which are present in almost all living organisms, constitute
the main components of many biological membranes. These membranes are selec-
tively permeable barriers around cells, and around organelles inside cells. However,
glycerophospholipids also have many other biological functions, for example as part
of cell signaling cascades.
Glycerophospholipids are useful for many applications, mainly due to their sur-
face activity. For example, they are used as emulsifiers in food and cosmetics.
Furthermore, glycerophospholipids constitute a key constituent of liposomes which
are used in cosmetics and as drug carriers. A general formula of glycerophospho-
lipids, together with the enzymes which can hydrolyze the different ester bonds in the
molecules, is shown in Figure 1. As will be shown later in the chapter, most of those
enzymes can be used to make ester bonds in the same positions.
14.2 Synthetic strategies
When glycerophospholipids are isolated from biological materials, the crude extracts
normally contain a complex mixture of molecular species containing different fatty
acids and different polar groups. Separation according to polar group can often be
carried out rather easily, and this is sufficient for many applications. However, the
separation of molecules differing in their fatty acid content is much more difficult
Figure 1. Glycerophospholipid molecule and the enzymes which can be used to break or form the
different ester bonds. R1 and R2 are alkyl groups of fatty acids, and X depends on the class of glycero-
phospholipid; in phosphatidylcholine X¼(CH 2 ) 2 N+(CH 3 ) 3.
Enzymes in Lipid Modification.Edited by Uwe T. Bornscheuer
Copyright2000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. ISBN: 3-527-30176-3