Figure 1
From: ProteinVolume: calculating molecular van der Waals and void volumes in proteins
Schematic diagram depicting surface and volume definitions. The solvent accessible surface is made by tracing out the center of solvent probes (blue circles) rolled around the entire protein surface. The molecular surface definition cleanly separates geometric or solvent-excluded volume (VSE) from the envelope volume (VE) reflecting to solute-solvent interactions. The molecular surface volume (VMS) is the sum of the van der Waals (VVDW) and void volumes (VVoid).