Table 1.

Selected Biochemical Databases

	KEGG36	MetaCyc [45]	PubChem [42]	ChEBI43	GMD34	HMDB1
Link	www.genome.jp/kegg/	www.genome.jp/kegg/	pubchem.ncbi.nlm.nih.gov/	www.ebi.ac.uk/chebi/	gmd.mpimp-golm.mpg.de/	www.hmdb.ca/
Type	Comprehensive	Comprehensive	Chemical	Chemical	Mass Spectral	Mass Spectral Comprehensive
Database Features	Genomes, genes, proteins, metabolites, drugs, diseases, pathways, visualizations	Genes, proteins, metabolites, pathways, interactive visualizations	Compound	Compound	Metabolites	Metabolites
Specificity	Generalized annotations, 2260 organism semi-specific annotations	Generalized annotations, 1939 organism specific annotations	Broad	Broad	Broad, plant heavy	Human