INVESTIGADORES
FIDELIO gerardo Daniel
congresos y reuniones científicas
Título:
Surface properties of amphiphilic peptides at air/water interface
Autor/es:
FIDELIO G.D
Lugar:
Caxambu
Reunión:
Conferencia; XXIX Reuniao Anual; 2014
Institución organizadora:
FeSBE
Resumen:
Surface Properties of
Amphiphilic peptides at Air/Water Interface Modern view of natural membranes has been updated
from the original vision emerged from the Fluid Mosaic Model of Singer and
Nicolson published in 1972. One of highlighted feature of the new vision is the acceptance of a high density of proteins mixed with lipids organized as a
bilayer forming a continuous hydrophobic/hydrophilic limit that dynamically
controls the function of biomembranes in the cell. Langmuir monolayers at the
air/water interface is practically the unique technique allowing the study of
the surface properties of peptides and proteins and their interaction with
lipids in a confined ?crowded? condition similar to the that found in
natural biomembranes. Even more, the experimental conditions, as the surface
covered proportion of the peptide compared with the lipid one or the degree of
surface compactness, are quite controlled at will by the investigator. Using
Langmuir monolayer many studies can be performed such us: ability of peptides
to absorb to clean air/water interfaces (tensio-active properties), to interact with organized lipid monolayers
(penetration), surface stability of spread protein/peptide sample,
peptide/lipid lateral miscibility, surface rheology, conformation and secondary
structure by PM-IRRAS and lateral topography by using the Brewster Angle Microscopy technique (BAM).
Even when the proteins and short
peptides are so diverse in sequence (and therefore amphiphilicity and structure)
some generalities can be achieved regarding to their surface behavior at
water/air interface. Water soluble amphipathic proteins and peptides acquire
similar surface properties independently they absorbed from bulk aqueous phase
or spread from aqueous or from an appropriate organic solvent solution; a
higher stability upon lateral compression is observed with hydrophobic peptides
with a higher tendency to adopt a β-sheet conformation
at the interface compared with those with a higher tendency to adopt an α-helix
and, in turn, this higher stability confers a greater tendency to remain
miscible in mixed lipid-peptide systems; some representative pure peptide
monolayers have similar properties than lipids when their surface
characteristics are compared (lateral stability and surface potential) and, a higher
liquid-expanded character of the lipid at the interface confers a more adequate
lateral environment for bidimensional miscibility. Finally,
amyloidogenic peptides such as Aβ1-42 amyloid peptide with a higher tendency to
adopt β-sheet
conformation has a remarkable shear elasticity modulus when compared to lytic melittin
compatible with a fiber-like topography at the surface found for the former.