INVESTIGADORES
OLIVEIRA Rafael Gustavo
congresos y reuniones científicas
Título:
Thermotropic phase behavior of isolated myelin membranes under different ionic content as observed by SAXS/SANS combination
Autor/es:
RAFAEL GUSTAVO OLIVEIRA; SCHNECK, E.; FUNARI, S. S.; DEMÉ, B.; TANAKA, M.; MAGGIO, B.
Lugar:
Grenoble, Francia
Reunión:
Workshop; BILL 2011 (Bilayers at Institute Laue Langevin); 2011
Institución organizadora:
Laue-Langevin Institute
Resumen:
The purified myelin membrane
is the starting material for the biochemical studies such as isolation of
detergent resistant membrane fractions. Normally, the last procedure involves
the extraction of lipids on non-ionic detergents under cooling. The
thermotropic behavior of purified myelin membranes is examined in the 5-46 ºC
for a series of different solvent systems by SAXS/WAXS and DSC. Additionally we
succeeded in producing planar multilayers of myelin on Si/SiO2
wafers by testing different spreading techniques. The objective here is to take
advantage of planar scattering geometry in SANS experiments, controlling the
ionic content of the aqueous media. The results with SAXS and SANS are
consistent in showing that, regardless of the aqueous media, the myelin
membrane becomes heterogeneous below room temperature. The heterogeneous state
is further stabilized by ionic media like physiological solution, then phase
coexistence persists up to the border of the physiological temperature. The
extreme case is the one of Ca2+ at high concentration (over 20 mM), then the phase
coexistence is permanent at least up to 46 ºC. Nevertheless, the relative
proportion of the phases, and thus probably the phase composition, markedly
changes with temperature. From a general point of view, it has been suggested
by multiple authors that cell membranes are set at the border of phase
transition or critical points for phase mixing. The results showed appear to
fit into this general framework.