For the binary systems the infrared spectra of the methylene deformation modes are shown at − 120 °C for DPPS MLVs (A), DPPC-d62 MLVs (B), DPPS MLVs + Mg2+ (C), and DPPC-d62 MLVs +Mg2+ (D). Pure lipid MLV assemblies are represented by the black broken line, while the mixed lipid MLV assemblies are represented as follows: 9:1 (dk. gray), 3:1 (gray), and 1:1 (lt. gray) of DPPS – DPPC-d62, respectively.