The Ligand Chemical Database for Enzyme Reactions (LIGAND) is designed to provide the linkage between chemical and biological aspects of life in the light of enzymatic reactions. The database consists of three sections: the ENZYME section, the COMPOUND section and the REACTION section.
The ENZYME section is a collection of all known enzymatic reactions classified according to the nomenclature of the International Union of Biochemistry and Molecular Biology (IUBMB):
International Union of Biochemistry and Molecular Biology,
"Enzyme Nomenclature: Recommendations (1992) of the Nomenclature
Committee of the International Union of Biochemistry and Molecular
Biology", Academic Press, New York (1992).
Now the result of the classification is reflected to the ExPASY ENZYME database developed by Dr. Amos Bairch at Swiss Institute of Bioinformatics. Some entries in the ENZYME section were taken from the database.
Each entry of ENZYME is identified by the EC (Enzyme Commission) number, and contains information of naming, chemical reactions, metabolic compounds, metabolic pathways, genes encoding the enzyme for several organisms, genetic diseases, and links to other databases including protein sequences and 3D structural data.
The COMPOUND section is a collection of metabolic compounds including substrates, products, and inhibitors. Each of the chemical substances that appear in the ENZYME section and KEGG/PATHWAY database is identified by an accession number and stored in this section. Each entry of COMPOUND contains information of naming, chemical formula, structural formula in a separate GIF file and a MOL file, metabolic pathways, related enzymes and CAS (Chemical Abstracts Service) registry number.
The REACTION section is a collection of chemical reactions that appear in the pathway diagrams of the KEGG/PATHWAY database as well as in the ENZYME section. It includes non-enzymatic reactions and enzymatic reactions whose EC numbers have not been assigned yet.
The LIGAND database is a major component of the DBGET/LinkDB integrated database system, providing useful links among the existing databases. LIGAND is tightly coupled to the metabolic pathway database of the KEGG system, providing links to the gene catalogs of a number of organisms.
As of October 1998, the numbers of data entries are as follows.
Please cite the following paper when making use of the LIGAND database:
Goto, S., Nishioka, T., and Kanehisa, M., "LIGAND: Chemical Database for Enzyme Reactions", Bioinformatics, 14:591-599 (1998).
E-mail: www@genome.ad.jp