RHEA is a database of biochemical reactions, initially populated with data fromIntEnz.
Its motivations and specification can be found in the IntEnz documentation web site.


  • Use of a controlled vocabulary (ChEBI) for referencing every chemical compound in IntEnz.
    Existing reactions in IntEnz - stored as free text - would be parsed to extract and map every compound, validating stoichiometry.
  • Unique identity for every reaction in IntEnz. One reaction could be referenced by several different EC numbers, avoiding redundancy in the database.
  • Having unique identifiers for reactions, a new identifier for enzymes based on the catalyzed reactions could be built. This new ID would be completely independent from the EC classification.
  • Being unique, RHEA reactions can belinked from/to other reaction databases: Reactome, KEGG reaction, SABIO...
  • Portability: reactions should be easy to import/export in common formats. To this end, BioPAX has been chosen.


The main RHEA subproject is the active development of a reaction ontology, requested independently by different people during the meetings held to gather requirements and suggestions about the projected IntEnz reaction database.
Among the existing reaction ontologies, REX has been chosen to this end.

In order to manage this and other ontologies, MONTY was conceived as a user friendly, multiuser system.