The influence of four laminin-derived peptides on bilayer organization is studied. Spectroscopic methods applied were based on pyrene fluorescence properties (quenching, I-1/I-3, and monomer/excimer equilibrium), asymmetric membrane fluorescence (NBD-PE/dithionite), and polarization fluorescence (TMA-DPH). Also, the ability of these peptides to release carboxyfluorescein entrapped in vesicles was determined. Results suggest that these peptides do not noticeably modify the packing and motion of lipids (in the gel state), but coat its surface, preventing penetration of quenchers and chemical reactants. Nevertheless, their presence promotes a soft release of entrapped CF after incubation at 37 degrees C. (c) 2005 Published by Elsevier Inc.