The influence of domain crowding on the lateral diffusion of ceramide-enriched domains in a sphingomyelin monolayer

N. WILKE Y B. MAGGIO.

AMER CHEMICAL SOC

Año: 2009 vol. 113 p. 12844 - 12844

n this paper, we analyze the Brownian motion of ceramide-enriched condensed domains immersed in a fluidsphingomyelin-enriched monolayer at the air-water interface. The diffusion coefficient of the domains isdetermined under different molecular packings and domain arrays, and the monolayer viscosity is calculated.With this approach, the effect of domain crowding and of intrinsic monolayer viscosity can be split. Wefound that, for mixed monolayers of palmitoylated sphingomyelin and ceramide, the monolayer viscositydepends on the lateral pressure and on the domain-domain distance. In a 9:1 proportion of sphingomyelin:ceramide, the viscosity is about 4 × 10-9 N s m-1 below 15 mN m-1 (continuum sphingomyelin phase in aliquid expanded state) and increases at higher lateral pressures (continuum phase in a condensed state). Theviscosity change with pressure is caused by both an increase of intrinsic viscosity and an increase in domaincrowd