Fluorimetric studies of the interactions of wheat puroindolines with polar lipids on the surface starch granules

•Lipids take part in puroindoline–starch interactions on starch granule surface.•Changes of protein conformation during interactions with liposomes were observed.•Negatively changed ligand has a strong impact on protein-lipid interactions.•Liposomal bilayer method comprises a good mean for protein-lipid interaction analysis.

The interactions of puroindolines with polar lipids were investigated using polarization of fluorescence probes preincorporated into a liposomal bilayer containing PC, PI, PS, MGDG, DGDG, and sulfolipids. The intrinsic fluorescence of Trp residue method was also used. Regardless of the kind of lipid used for liposome preparation, proteins interacted with the liposomes. Conformational changes of the proteins were observed simultaneously with the change in the molecule packing in the lipid bilayer of the liposomes. Puroindoline interactions with the surface of the liposomes have explicit importance for the net charge of this surface. The strong interaction between the proteins and lipids takes place in the presence of a ligand with a negative charge. The obtained results confirm that lipids take part in puroindoline–starch granule surface interactions.