title: Packing and electrostatic behavior of sn-2-docosahexaenoyl and -arachidonoyl phosphoglycerides.
abstract: Mammalian synaptic membranes appear to contain high proportions of specific, sn-1-stearoyl-2-docosahexaenoyl- and sn-1-stearoyl-2-arachidonoyl phosphoglycerides, but the structural significance of this is unclear. Here we used a standardized approach to compare the properties of homogeneous monolayers of the corresponding phosphatidylcholines, phosphatidylethanolamines, phosphatidylserines, and phosphatidic acids with those of control monolayers of sn-1-stearoyl-2-oleoyl- and sn-1-palmitoyl-2-oleoyl phosphoglycerides. Major findings were: 1), that the presence of an sn-2-docosahexaenoyl group or an sn-2-arachidonoyl group increases the molecular areas of phosphoglycerides by 3.8 A(2) (7%) relative to the presence of an sn-2-oleoyl group; 2), that the phosphorylcholine headgroup independently increases molecular areas by a larger amount, 7.1 A(2) (13%); and 3), that the dipole moments of species having an arachidonoyl moiety or an oleoyl moiety are 83 mD (19%) higher than those of comparable docosahexaenoic acid-containing phosphoglycerides. These and other results provide new information about the molecular packing properties of polyenoic phosphoglycerides and raise important questions about the role of these phosphoglycerides in synapses.
mesh_terms: D004281:Docosahexaenoic Acids / Q000737:chemistry*; D004563:Electrochemistry / Q000379:methods*; D020404:Glycerophospholipids / Q000737:chemistry* / Q000145:classification; D008244:Lysophosphatidylcholines / Q000737:chemistry*; D046911:Macromolecular Substances; D008274:Magnesium / Q000737:chemistry*; D008560:Membrane Fluidity; D008563:Membrane Lipids / Q000737:chemistry*; D008968:Molecular Conformation; D010713:Phosphatidylcholines / Q000737:chemistry*; D013500:Surface Tension; D013570:Synaptic Membranes / Q000737:chemistry*
chemical_list: C462319:1-strearoyl-2-arachidonyl-sn-glycero-3-phosphatidylcholine; D020404:Glycerophospholipids; D008244:Lysophosphatidylcholines; D046911:Macromolecular Substances; D008563:Membrane Lipids; D010713:Phosphatidylcholines; C090324:docosahexaenoyl lysophosphatidylcholine; D004281:Docosahexaenoic Acids; D008274:Magnesium