Effect of water and salts in the phase separation of isolated natural membranes

Campinas

Otro; Activity Report LNLS; 2009

Laboratorio Nacional de Luz Sincrotron

Myelin is the membrane material wrapping axons in nervesand providing for electrical isolation essential for fast nerveimpulse propagation. From the structural point of view isquite unique among cell membranes. Its particular multilayeredstructure, allows for x-ray diffraction. The isolated membraneretains this particular structure, allowing also for thistechnique. The homogeneity/heterogeneity of cell membranesis an open issue under current research. We characterize theresponse of the membrane to environmental variables to correlatethe behavior with the one observed in spread monolayersat the air/water interface [1]. This is a convenient systemto manipulate biological interfaces. Previous SAXS measurementsaimed at detecting phase separation on isolated myelinmembranes were performed (beamline A2 at Hasylab-Desy)using capillaries with a relatively low level of water (around60%). We now wanted to check if this amount of water couldinduce unwanted effects due to partial hydration of the membrane.