Fig. 8
From: A novel protein descriptor for the prediction of drug binding sites
A slightly modified version of LIGSITE. The voxels represent the solvent, the green dots are the protein atoms, and the white area is the protein contour. The red lines are the scanning lines in the x direction with a step of 1Å. When a scanning line experiences a protein-solvent-protein event, the voxel contained in the intermediate solvent undergoes a PSP event indicated by the purple voxels. In three-dimensional case, proteins are scanned in seven directions including x,y,z and four diagonal directions