Relationship between the mobility of phosphocholine headgroup and the protein-liposome interaction: a dielectric spectroscopic study.

Proteins could affect the headgroup mobility of phospholipid within liposome membranes through the protein-liposome interaction. The variation of headgroup mobility of phospholipid was then investigated by using the dielectric dispersion analysis. The eight proteins (Mw = 4.2-28.7 kDa) were used to investigate the protein-liposome interaction. It has been revealed that the strength of the protein-liposome interaction at 25 °C was linearly correlated with the stability of intramolecular hydrogen bondings of proteins, better than with their hydrophobicity and the surface charge density. Overall, liposomes composed of binary lipid system, appeared to strongly interact with proteins, in contrast to liposomes composed of single, ternary, and quaternary lipid systems. This is probably because liposomes composed of binary lipid system favored to form the microscopic environment where proteins could interact. The present result suggested the heterogeneous phase state of lipid membranes was one of dominant factors for the interaction between proteins and lipid membranes.