Ceramide acyl chain length markedly influences miscibility with palmitoyl sphingomyelin in bilayer membranes

A1 Journal article (refereed)


Internal Authors/Editors


Publication Details

List of Authors: Westerlund B, Grandell PM, Isaksson YJE, Slotte JP
Publisher: SPRINGER
Publication year: 2010
Journal: European Biophysics Journal
Journal acronym: EUR BIOPHYS J BIOPHY
Volume number: 39
Issue number: 8
Start page: 1117
End page: 1128
Number of pages: 12
ISSN: 0175-7571
eISSN: 1432-1017


Abstract

Ceramides are precursors of major sphingolipids and can be important cellular effectors. The biological effects of ceramides have been suggested to stem from their biophysical effects on membrane structure affecting the lateral and transbilayer organization of other membrane components. In this study we investigated the effect of acyl chain composition in ceramides (C4-C24:1) on their miscibility with N-palmitoyl-sphingomyelin (PSM) using differential scanning calorimetry. We found that short-chain (C4 and C8) ceramides induced phase separation and lowered the T (m) and enthalpy of the PSM endotherm. We conclude that short-chain ceramides were more miscible in the fluid-phase than in the gel-phase PSM bilayers. Long-chain ceramides induced apparent heterogeneity in the bilayers. The main PSM endotherm decreased in cooperativity and enthalpy with increasing ceramide concentration. New ceramide-enriched components could be seen in the thermograms at all ceramide concentrations above X (Cer) = 0.05. These broad components had higher T (m) values than pure PSM. C24:1 ceramide exhibited complex behavior in the PSM bilayers. The miscibility of C24:1 ceramide with PSM at low (X (Cer) = 0.05-0.10) concentrations was exceptionally good according to the cooperativity of the transition. At higher concentrations, multiple components were detected, which might have arisen from interdigitated gel-phases formed by this very asymmetric ceramide. The results of this study indicate that short-chain and long-chain ceramides have very different effects on the sphingomyelin bilayers. There also seems to be a correlation between their miscibility in binary systems and the effect of ceramides of different hydrophobic length on sphingomyelin-rich domains in multicomponent membranes.


Keywords

Differential scanning calorimetry, Melting temperature, Membrane structure, Molecular structure

Last updated on 2019-22-07 at 06:36