The onset of Triton X-100 solubilization of sphingomyelin/ceramide bilayers: effects of temperature and composition

The early stages of Triton X-100 solubilization of bilayers consisting of sphingomyelin/ceramide (SM/Cer) mixtures have been studied using a combination of calorimetric and spectroscopic techniques. Compositions based on sphingomyelin, containing up to 30 mol% Cer, at 4, 20 and 50 °C have been examined. The presence of Cer does not modify the affinity (in terms of ΔG of binding per mol total lipid) of the SM-based bilayers for Triton X-100, although it does increase the amount of detergent required for the onset of solubilization. At 50 °C more detergent was required to solubilize the SM/Cer bilayers than at 20 °C. The data can be rationalized in terms of lipid and detergent geometries and interactions (Lichtenberg et al., 2013).

► Ceramide does not change the affinity of sphingomyelin-based bilayers for Triton X-100.
► Ceramide increases the amount of Triton X-100 required to start solubilization of sphingomyelin/ceramide bilayers.
► Sphingomyelin–ceramide bilayers require more detergent for solubilization at 50 °C than at 20 °C.