Duplicates. On average, 59% of the fragments in each subpocket were present in more than one structure (referred to as duplicates). This can be explained by the traditional medicinal chemistry approach to study a wide range of decorating groups around a shared molecular scaffold and thereby explore structure-activity relationships. Such approaches can result in the crystallization of multiple analogs from the same series. However, this finding also highlights the limited chemical diversity of the known kinase inhibitor space (considering molecules with available crystal structures only). The highest relative number of duplicates was identified in GA (70%), for the other subpockets the values do not differ largely from the average (Figure .B). The higher share of duplicates in GA could be explained by the generally smaller fragment size in this subpocket (compared to AP, FP, and SE, see Physicochemical properties. In order to identify particularities in the chemical space of the different subpocket pools, standard chemical descriptors were calculated. These include (i) hydrogen bond donors and acceptors (HBD and HBA), (ii) logP values, and (iii) molecule size as in the number of heavy atoms. The distributions of these descriptors for each subpocket pool are displayed as boxplots in Figure .A, while excluding duplicates.