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 degrees C have been examined. The presence of Cer does not modify the affinity (in terms of Delta G 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 degrees C more detergent was required to solubilize the SM/Cer bilayers than at 20 degrees C. The data can be rationalized in terms of lipid and detergent geometries and interactions (Lichtenberg et al., 2013). (C) 2013 Elsevier Ireland Ltd. All rights reserved.