Cooling induces phase separation in membranes derived from isolated CNS myelin

PUSTERLA, JULIO M.; SCHNECK, EMANUEL; FUNARI, SÉRGIO S.; DEMÉ, BRUNO; TANAKA, MOTOMU; OLIVEIRA, RAFAEL G.

PLOS ONE

PUBLIC LIBRARY SCIENCE

Año: 2017 vol. 12

1932-6203

urified myelin membranes (PMMs) are the starting material for biochemical analyses such as the isolation of detergent-insoluble glycosphingolipid-rich domains (DIGs), which are believed to be representatives of functional lipid rafts. The normal DIGs isolation protocol involves the extraction of lipids under moderate cooling. Here, we thus address the influence of cooling on the structure of PMMs and its sub-fractions. Thermodynamic and structural aspects of periodic, multilamellar PMMs are examined between 4C and 45C and in various biologically relevant aqueous solutions. The phase behavior is investigated by small-angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC). Complementary neutron diffraction (ND) experiments with solid-supported myelin multilayers confirm that the phase behavior is unaffected by planar confinement. SAXS and ND consistently show that multilamellar PMMs in pure water become heterogeneous when cooled by more than 10?15C below physiological