These data are based on a proprietary database of publicly-available molecules, the MDL Drug Data Report (MDDR). Interested readers should contact Symyx Technologies directly. Information on the most recent version of the MDDR database is located at Symyx's website:

http://www.symyx.com/products/databases/bioactivity/mddr

The MDDR database was prepared for this article as described in the following excerpt from the Methods:

Drug sets were extracted from the MDDR, a compilation of about 169,000 drug-like ligands in 688 activity classes, each targeting a specific enzyme (designated by the Enzyme Commission (E.C.) number). The subset of this database for which mappings between enzymes and the MDDR drug classes were available was used. These mappings were based on a previous study that maps E.C. numbers, GPCRs, ion channels and nuclear receptors to MDDR activity classes [1]. Only sets containing five or more ligands were used. Salts and fragments were removed, ligand protonation was normalized and duplicate molecules were removed. Of the 688 targets in the MDDR, 97 were excluded as having too few ligands (<5), and another 345 targets were excluded because their definitions did not describe a molecular target, e.g., drugs associated only with an annotation such as "Anticancer" were not used. The remaining 246 enzyme targets were together associated with a total of 65,241 unique ligands, with a median and mean of 124 and 289 drug ligands per target. For further details, see Keiser et al. [2].

1. Schuffenhauer A, Zimmermann J, Stoop R, van der Vyver JJ, Lecchini S, et al. (2002) An ontology for pharmaceutical ligands and its application for in silico screening and library design. J Chem Inf Comput Sci 42: 947-955.

2. Keiser MJ, Roth BL, Armbruster BN, Ernsberger P, Irwin JJ, et al. (2007) Relating protein pharmacology by ligand chemistry. Nat Biotechnol 25: 197-206.