Figure 1

Rh2 interacts more favorably with membrane pSM and DOPC than with Chol. (A) Chemical structure of Rh2. (B,C) IMPALA simulation of the most favorable position of Rh2 into an implicit membrane 36 Å thick. (B) Energy profile of Rh2 traversing an implicit lipid bilayer. X-axis corresponds to the position of the center of mass of the saponin across the bilayer expressed in Ångström. Y-axis corresponds to total restraint energy expressed in kcal/mol. The solid vertical lines in different colors represent the different planar surfaces from the left to the right: water/membrane interface (pink), the lipid polar head/alkyl chain interface (purple), and the center of the bilayer (yellow). The vertical dotted line at ±15.75 Å corresponds to the interface between the hydrophobic and hydrophilic parts of the bilayer. (C) The most stable position of Rh2 into the implicit bilayer. The different planar surfaces represent the same solid vertical lines described in (B). Carbon atoms are dark grey, Hydrogens white, Nitrogens light blue and Oxygens red. (D,E) Interaction between Rh2 and pSM, Chol or DOPC was calculated by Hypermatrix docking method. (D) Relative total energy of interaction values for the interaction between a central molecule Rh2 and surrounding pSM, Chol or DOPC. Grey and white portions are the apolar and polar components of the energies, respectively. (E) Molecular assemblies of a Rh2 molecule interacting with a single pSM, Chol or DOPC molecule.