Nanosized Phase Segregation of Sphingomyelin and Dihydrosphigomyelin in Unsaturated Phosphatidylcholine Binary Membranes without Cholesterol.

A1 Journal article (refereed)


Internal Authors/Editors


Publication Details

List of Authors: Yasuda T, Slotte JP, Murata M
Publisher: AMER CHEMICAL SOC
Publication year: 2018
Journal: Langmuir
Journal acronym: Langmuir
Volume number: 34
Issue number: 44
Start page: 13426
End page: 13437
ISSN: 1520-5827


Abstract

In this study, we applied fluorescence
spectroscopy, differential scanning calorimetry (DSC), and( 2)H NMR to
elucidate the properties of nanoscopic segregated domains in
stearoylsphingomyelin (SSM)/dioleoylphosphatidylcholine (DOPC) and
dihydrostearoylsphingomyelin (dhSSM)/DOPC binary membranes. The results
obtained from fluorescence measurements suggest the existence of
gel-like domains with high fluidity in both SSM and dhSSM macroscopic
gel phases. The DSC thermograms showed that DOPC destabilizes SM-rich
gel-like domains to a much lesser extent compared to the same amount of
cholesterol. It was also found that a stable lateral segregation occurs
without cholesterol, indicating that SSM itself undergoes homophilic
interactions to form small gel- like domains. H-2 NMR experiments
disclosed differences in the temperature-dependent ordering of SSM/DOPC
and dhSSM/ DOPC bilayers; the dhSSM membrane showed less miscibility
with the DOPC fluid phase, higher thermal stability, and tighter
packing. In addition, the NMR results suggest the formation of mid-sized
gel-like aggregates consisting of dhSSM. These differences could be
accounted for by homophilic interactions, as previously reported (Yasuda
et al. Biophys. J. 2016, 110, 431 -440). In the absence of cholesterol,
the moderately strong sphingomyelin (SM)/SM affinity results in the
formation of small gel-like domains, whereas a stronger dhSSM/dhSSM
affinity leads to larger gel-like domains. Considering the similar
physicochemical features of SSM and dhSSM, the present results suggest
that the formation of nanosized domains of SM is better characterized by
homophilic interactions than by SM-cholesterol interplay. These effects
are considered important to the ordered domain formation of SMs in
biological membranes.

Last updated on 2019-19-09 at 05:22