Study of tensioactive properties of casein signal peptides and their interactions with phospholipids

The high degree of sequence conservation in casein signal peptides reflects their unique functional properties. A series of casein signal peptides and derivatives was synthesized in order to study their insertion in phospholipidic mono- and bilayer structures. Most of these amphiphilic peptides were found to be highly tensio-active. Their conformations differ and are solvent dependent. Fluorescence anisotropy measurements showed that all the peptides of the series could interact with dimyristoylphosphatidyl -choline and -glycerol when mixed with the lipids prior to hydration of the liposomes. The most soluble peptide, P6, was selected for insertion experiments in multilamellar vesicles. Its interaction with liposomes is efficient and rapid, being temperature dependent. On the one hand, the physico-chemical measures of interactions of signal peptides of casein beta and alpha s2 confirm their mutual genetic relationship, and on the other hand they show the divergence of casein beta and alpha s2 from casein kappa signal peptide.