ENZYME: Enzyme nomenclature database at ExPASy

http://expasy.org/enzyme

Enzyme Nomenclature

https://www.qmul.ac.uk/sbcs/iubmb/enzyme/

ExplorEnz: The Enzyme Database

http://www.enzyme-database.org/

BRENDA: The Comprehensive Enzyme Information System

http://www.brenda-enzymes.info/

Swiss-Prot: Protein knowledgebase

http://expasy.org/sprot

NCBI PubMed: Comprehensive resource of literature

http://www.ncbi.nlm.nih.gov/sites/entrez?db=PubMed

Thermodynamics of Enzyme-Catalyzed Reactions

http://xpdb.nist.gov/enzyme_thermodynamics/

KEGG: Kyoto Encyclopedia of Genes and Genomes

http://www.genome.jp/kegg/

CAZy: Carbohydrate-Active enZymes

http://www.cazy.org/

Botnam Guide to Enzymes

https://botnam.com/enzymes/