INVESTIGADORES
DUPUY Fernando Gabriel
artículos
Título:
Ceramide N-Acyl Chain Length: A Determinant of Bidimensional Transitions, Condensed Domain Morphology, and Interfacial Thickness.
Autor/es:
DUPUY, FERNANDO; FANANI, MARÍA LAURA; MAGGIO, BRUNO
Revista:
LANGMUIR
Editorial:
AMER CHEMICAL SOC
Referencias:
Año: 2011 vol. 27 p. 3783 - 3791
ISSN:
0743-7463
Resumen:
Several lipids of biological interest are able to form monomolecular
surfaces with a rich variety of thickness and lateral topography that
can be precisely controlled by defined variations of the film
composition. Ceramide is one of the simplest sphingolipids, consisting
of a sphingosine base N-linked to a fatty acid, and is a membrane
mediator for cell-signaling events. In this work, films of ceramides
N-acylated with the saturated fatty acids C10, C12, C14, and C16 were
studied at the air−aqueous interface. The dipole moment contribution
(from surface potential measurements) and the surface topography and
thickness (as revealed by Brewster angle microscopy) were measured
simultaneously with the surface pressure at different molecular areas.
Several surface features were observed depending on the asymmetry
between the sphingosine and the N-linked acyl chains. At 21 °C, the
C16:0 and C14:0 ceramides showed condensed isotherms and the film
topography revealed solid film patches (17.3−15.7 Å thick) that
coalesced into a homogeneous surface by further compression. On the
other hand, in the more asymmetric C12:0 and C10:0 ceramides, liquid
expanded states and liquid expanded−condensed transitions occurred. In
the phase coexistence region, the condensed state of these compounds
formed flowerlike domains (11.1−13.3 Å thick). C12:0 ceramide domains
were larger and more densely branched than those of C10:0 ceramide. Both
the film thickness and the surface dipole moment of the condensed state
increased with ceramide N-acyl chain length. Bending of the sphingosine
chain over the N-linked acyl chain in the more asymmetric ceramides can
account for the variation of the surface electrostatics, topography,
and thickness of the films with the acyl chain mismatch.