Sphingomyelinase-induced non-equilibrium phenomena in biointerfaces

MARIA LAURA FANANI, STEFFEN HARTEL, JORGE JARA Y BRUNO MAGGIO

Madrid España

Congreso; VI Congreso Iberoamericano de Biofísica; 2006

Universidad Computense de Madrid

Sphingomyelinase (SMase) is a membrane associated enzyme that catalyzes the hydrolysis of Sphingomyelin (SM) to Ceramide (Cer) and Phosphocholine. The real time visualization by epifluorescence microscopy of its action against air/buffer SM monolayers shows the generation of laterally segregated Cer-enriched domains with a fractal-like boundary morphology and long-range lattice organization. Pre-mixed films of SM and different proportions of Cer have shown (Fanani et al., 2002, Hartel et al., 2005) mostly randomly distributed Cer-enriched domains, with compact rounded-boundary shapes, containing a higher proportion of SM compared to the SMase-generated domains. The morphology, dipolar properties and lattice organization of the enzyme-generated domains change over time after halting of activity and appear as a non-equilibrium phenomenon with a slow relaxation process. This is not seen in pre-mixed enzyme-free films. The crossover from fractal-like far-from-equilibrium domain topography to compact morphology is studied. These results introduce a new perspective for focusing on crosstalk between the dynamics of lateral structure in biointerfaces and biocatalytic activity relevant to cell signaling events.