12 Phospholipases Used in Lipid
Transformations
Renate Ulbrich-Hofmann
Abbreviations
AOT bis-(2-ethylhexyl)sodium sulfosuccinate
GPI glycosylphosphatidylinositol
HEPES N-(2-hydroxyethyl)-piperazine-N’-ethanesulfonic acid
Lyso-PC lyso-phosphatidylcholine
PC phosphatidylcholine
PE phosphatidylethanolamine
PG phosphatidylglycerol
PI phosphatidylinositol
PLA 1 phospholipase A 1
PLA 2 phospholipase A 2
PLC phospholipase C
PLD phospholipase D
PS phosphatidylserine
SDS sodium dodecylsulfate
Tris tris(hydroxymethyl)aminomethane
12.1 Classificationofphospholipasesandtheirsubstrates
Phospholipases are a group of enzymes whose natural function consists of the hy-
drolysis of phospholipids. This class of compounds represent the main components
of biological membranes. Phospholipids also occur in large amounts in plant seeds
and chicken eggs. Some phospholipid members are biological signal molecules;
phospholipases, therefore, effect the metabolism, construction, and reorganization
of biological membranes, and are involved in signal cascades. The molecular fea-
ture of phospholipids is the diester structure of phosphoric acid in which one alco-
holic moiety (X) is polar and the other (Y) is nonpolar (Figure 1). The third acidic
function of the phosphoric acid is ionized at physiological pH. Most natural phos-
pholipids are glycerophospholipids (phosphatides), where the nonpolar alcoholic
component is a 1,2-diacyl-sn-glycerol (Figure 1). The esterification to phosphoric
acid is insn-3 position of the glycerol moiety. The notationsnrefers to the ‘stereo-
specific numbering’ adopted by IUPAC-IUB (IUPAC-IUB Commission on Bio-
chemical Nomenclature, 1978a,b). As polar alcoholic components, charged or non-
charged compounds such as choline, ethanolamine (both positively charged), serine
(zwitterionic), inositol and glycerol (both noncharged) occur, yielding either neutral
or negatively charged phospholipids. Inositol can be further modified by one or more
Enzymesin LipidModification.Editedby UweT. Bornscheuer
Copyright 2000 Wiley-VCHVerlagGmbH& Co. KGaA,Weinheim.ISBN:3-527-30176-3
