Fig. 5

Heatmaps of Grad-CAM analyses and presentations of input features. a Example of a protein–ligand complex whose PDB ID was 1a28 from the training set. b 2D protein–ligand interactions of 1a28. c Example of a protein–ligand complex whose PDB ID was 1a30 from the CASF-2016 test set. d 2D protein–ligand interactions of 1a30. In a and c, the red spheres represent oxygen atoms of the ligand, the orange spheres represent nitrogen atoms of the ligand, the yellow spheres represent carbon atoms of the ligand and the small blue spheres represent the atoms of the protein. Hydrogen atoms are not shown on the graph for viewing purposes. The heatmap is colored from cyan to purple. In b and d, the green dashed line indicates hydrogen bonds and the red arc areas indicate hydrophobic interactions. a and c were drawn by Mayavi. b and d were generated with LigPlot + [46]