Fig. 2

Fragmentation of PDB compounds. A The bar plot shows the amount of PDB compounds by the number of fragments obtained after fragmentation. Most of the compounds are fragmented from 2 to 6 fragments. The compound at the bottom is an example of fragmentation with three fragments F1, F2 and F3. B The bar plot shows the frequency of fragment among the compounds (x axis shows on how many compounds is a fragment found). Most of them are present in just one compound, but others are highly frequent. The fragment I at the bottom left is present in only one compound, whereas the fragment II on the right is part of 65 different compounds