INVESTIGADORES
WILKE natalia
congresos y reuniones científicas
Título:
XXXV Influence of electrostatics on the topography and charged component distribution in a complex mixture monolayer
Autor/es:
C. M. ROSETTI, N. WILKE, MIZUTAMARI K, RODRIGUEZ P, MAGGIO B
Reunión:
Congreso; Reunión anual de la Sociedad Argentina de Biofísica; 2006
Resumen:
The
mixture of myelin lipids segregates into two phases at surface pressures lower
than 1 mN m-1. This was observed by the addition of 0.5 mole % of a
fluorescent lipid probe that partitions unequally among the phases. The phase
segregation is stabilized by the addition of myelin basic protein (MBP), which
partitions to the probe-enriched phase.
Oliveira et al. [1] showed that in whole myelin monolayers, some of
the negatively charged lipid components segregate from the positively charged
MBP. The aim of this work is to analyze the effect of electrostatics on the
domain stability and the partition of charged components among the phases. To
this purpose, different concentrations of positively and negatively charged
fluorescent molecules were added to the lipid-protein mixture. The phase-fusion
pressures, the migration of domains under the influence of an external electric
field and the probe partition in films on different subphases were studied
using epifluorescence microscopy coupled to a Langmuir balance. The results
indicate that low concentration of charged fluorescent probes markedly modifies
the phase coexistence stability. The influence of the electrostatic properties
of the molecule on the partition coefficient was analyzed from the dependence
of the latter with the ionic strength of the subphase. The observed migration
of domains under an electric field corresponds to dipoles oriented with the
resultant positive end pointing toward
the subphase [2], apparently in disagreement with the measured surface
potential density in monolayers of the pure component and the net charge of the
MBP. An insight of the influence of electrostatics on the phase stability and
component distribution in a complex mixed monolayer was obtained by varying the
probe concentration of different charged probes on subphases of different ionic
strength.