Fluorescence study on aggregated lysozyme and lipid bilayer interactions

Fluorescent probes 1,6-diphenyl-1,3,5-hexatriene (DPH), pyrene, 4-dimethylaminochalcone (DMC) and 4-p-(dimethylaminostyryl)-1-dodecylpyridinium (DSP-12) have been utilized to monitor the impact of lysozyme (Lz) oligomers on physicochemical properties of phosphatidylcholine/cardiolipin (PC/CL) membranes. Analysis of spectral responses of the employed probes revealed the reduction of membrane free volume and dehydration of lipid bilayer surface upon incorporation of Lz self-assemblies. Hydrophobic interactions were found to control the binding of Lz oligomers to the lipid bilayer. Comparison of the effects of Lz monomers, oligomers and fibrils showed that soluble oligomeric intermediates exert the most destructive influence on membrane properties.

► Protein fibrillization alters its bilayer-modifying properties.
► Soluble lysozyme oligomers produce dehydration and condensation of lipid bilayer.
► Membranotropic activity of oligomeric lysozyme is hydrophobically controlled.