title: Creation of a free, Internet-accessible database: the Multiple Target Ligand Database.
abstract: BACKGROUND
  Polypharmacology plays an important part in drug discovery, and remains a major challenge in drug development. Identification of the underlying polypharmacology of a drug, as well as development of polypharmacological drugs, have become important issues in the pharmaceutical industry and academia.
  
  
  METHODS
  Herein, through data mining of the Protein Data Bank (PDB), a free, Internet-accessible database called the Multiple Target Ligand Database (MTLD; www.mtdcadd.com) was constructed. The MTLD contains 1,732 multiple-target ligands (MTLs) which bind to 14,996 binding sites extracted from 12,759 PDB structures. Among MTLs, 222 entries are approved drugs and 1,334 entries are drug-like compounds. The MTLD could be an extremely useful tool in the development of polypharmacological drugs. It also sheds light on the side effects of drugs through anticipation of their multiple functions and similarities in the binding sites of multiple targets. The entire database is free for online searching, browsing, and downloading.
  
  
  CONCLUSIONS
  As a crucial expansion of the PDB, increasing numbers of MTLs will be included in the MTLD. Eventually, it will become an efficient platform to obtain useful information on MTLs and their underlying polypharmacology.
authors.affiliation: North China Institute of Science and Technology, Beijing, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Chen
authors.affiliation: Institute of Medicinal Biotechnology, Chinese Academy of Medical Science, Beijing, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: He
authors.affiliation: Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC Canada.
authors.forename: Jianhui
authors.initials: J
authors.lastname: Wu
authors.affiliation: Institute of Medicinal Biotechnology, Chinese Academy of Medical Science, Beijing, China.
authors.forename: Jinming
authors.initials: J
authors.lastname: Zhou
keywords: Database; Drug discovery; Multiple-target ligands; Polypharmacology