Ec numbers

The EC numbers (Enzyme Commission numbers) form a numerical classification system for enzymes. Each EC number consists of four numbers separated by periods. Strictly speaking, it is not the enzyme itself but the reaction it catalyses that is categorised. Thus, unrelated enzymes that catalyse the same reaction may be assigned the same EC number.

Currently more than 2500 enzymes are known. These can be classified and named according to their occurrence in nature, their function in metabolism, their functional groups or their physical properties.

Internationally accepted is a classification based on effect specificity (EC nomenclature = acronym for "enzyme commission"). According to this classification enzymes are divided into 7 main classes:

• EC1: Oxidoreductases (dehydrogenases, oxygenases, reductases). Examples are cytochrome P450 monooxidases, cyclooxygenases, glutamate dehydrogenases (GDH, GLDH)
• EC2:Transferases (transfer aldehyde, amino, glycosyl and other groups); e.g. transaminases (aminotransferases such as GOT and GPT). Furthermore also the group of kinases and others
• EC3: hydrolases (older name: synthetases): catalyse the linking of two molecules by forming a covalent bond (C-C, C-O, C-N and others); e.g. carboxylases
• EC 4:-Lyases (non-hydrolytic addition or elimination of molecular groups) e.g. decarboxylases, aldolases, synthases
• EC 5: Isomerases (catalysing intramolecular transformation) e.g. racemases, mutases,
• EC 6:-Ligases (catalyse the covalent linkage by means of high-energy cofactors ) e.g. synthetases, carboxylases
• EC 7:-Translocases (catalyse the transport of substances at or through cell membranes)