Miscibility of acyl-chain defined phosphatidylcholines with N-palmitoyl sphingomyelin in bilayer membranes.
In this study we have used differential scanning calorimetry (DSC) to study the miscibility of different saturated phosphatidylcholines (PCs) with D-erythro-N-palmitoyl-sphingomyelin (16:0-SM). Information about the miscibility was obtained by observing the thermotropic phase behavior of binary mixtures of saturated PCs and 16:0-SM. The results obtained showed that PC miscibility in 16:0-SM was markedly affected by the PC acyl-chain composition. According to phase diagrams prepared from DSC data and the mid-transition temperatures of the main phase transition, the PC which formed the most ideal mixture with 16:0-SM was di-14:0-PC. However, the cooperativity of the main transition in PC/16:0-SM bilayers increased until the average acyl-chain length in the PC reached 15 carbons. Based on the criteria of the most ideal miscibility or the highest cooperativity of the main transition, we conclude that di-14:0-PC, 15:0/15:0-PC, and 14:0/16:0-PC interacted most favorably with 16:0-SM in bilayer membranes. Di-16:0-PC, to which 16:0-SM is often compared in biophysical studies, showed much less ideal miscibility.
Térová
Bohdana
B
Department of Biochemistry and Pharmacy, ABO AKADEMI UNIVERSITY, PO Box 66, FIN 20521 Turku, Finland.
Slotte
J Peter
JP
Nyholm
Thomas K M
TK
D000215:Acylation; D055592:Biophysical Phenomena; D001703:Biophysics; D002152:Calorimetry, Differential Scanning; D008051:Lipid Bilayers; D008566:Membranes / Q000737:chemistry*; D008956:Models, Chemical; D008968:Molecular Conformation; D010713:Phosphatidylcholines / Q000737:chemistry*; D013109:Sphingomyelins / Q000737:chemistry*; D013696:Temperature
D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D013109:Sphingomyelins