Lipid arrangement in fluid model membranes: analysis by cross-linking of phosphatidylethanolamines

Binary mixtures of fluid phase phosphatidylethanolamines at pH 10 were treated with the bifunctional cross-linking reagent dimethylsuberimidate. Analysis of the dimeric species formed demonstrated that the phospholipid species in dimyristoylphosphatidylethanolamine/dielaidoylphosphatidylethanolamine mixtures at 52 degrees C and dielaidoylphosphatidylethanolamine/dilauroylphosphatidylethanolamine mixtures at 41 degrees C were randomly arranged. Analysis of the dimeric species formed in dipalmitoylphosphatidylethanolamine/dioleoylphosphatidylethanolamine mixtures at 68 degrees C showed that this mixture was very close to being randomly arranged, with just a slight propensity of like phospholipid species to cluster.