Polymorphism of the 1-palmitoyl-2-arachidonoyl-phosphatidyl-ethanolamine/dimyristoyl-phos phatidylmethanol mixture, a phospholipase A2 substrate.
The polymorphism of the equimolar mixture of 1-palmitoyl-2-arachidonoyl-phosphatidylethanolamine (PAPE) and dimyristoyl-phosphatidylmethanol (DMPM) was examined by infrared and 31P nuclear magnetic resonance spectroscopy to determine the suitability of this widely used but yet uncharacterized lipid mixture as a phospholipase A2 substrate. The results show that the mixture undergoes a gel-to-liquid crystalline phase transition between 12 and 35 degrees C. The transitions of the individual lipids were also examined. We report that the temperature of the gel-to-liquid crystalline phase transition of DMPM is 40 degrees C. At 2 degrees C, PAPE exists in the fluid lamellar form. This lipid undergoes a lamellar-to-inverted hexagonal phase transition at 31 degrees C. In conclusion, the equimolar PAPE/DMPM mixture forms fluid lamellar phase at the physiological temperature. However, the upper end of the gel-to-liquid crystalline phase transition of the mixture is really close to the physiological temperature and this situation is a serious source of potential artefacts.
Jacob
M
M
GREIB, Département de Chimie-Biologie, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, G9A 5H7, Canada.
Salesse
C
C
Lafleur
M
M
D020404:Glycerophospholipids / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D010714:Phosphatidylethanolamines / Q000737:chemistry*; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D013055:Spectrophotometry, Infrared
C096875:1-palmitoyl-2-arachidonyl-glycero-3-phosphoethanolamine; D020404:Glycerophospholipids; D008051:Lipid Bilayers; D010714:Phosphatidylethanolamines; C029313:dimyristoylmethylphosphatidic acid; D010741:Phospholipases A; D054467:Phospholipases A2