EC 3. Hydrolases

EC 3.1 Acting on ester bonds

This subclass contains the esterase enzymes. The esterases are subdivided into: carboxylic-ester hydrolases (EC 3.1.1), thioester hydrolases (EC 3.1.2), phosphoric-monoester hydrolases, the phosphatases (EC 3.1.3), phosphoric-diester hydrolases (EC 3.1.4), triphosphoric-monoester hydrolases (EC 3.1.5), sulfuric-ester hydrolases, the sulfatases (EC 3.1.6), diphosphoric monoesterases (EC 3.1.7) and phosphoric-triester hydrolases (EC 3.1.8). The nucleases, previously included under EC 3.1.4, are now placed in a number of new sub-subclasses: the exonucleases (EC 3.1.11-16) and the endonucleases (EC 3.1.21-31).

EC 3.1.23 and EC 3.1.24
In a previous edition, site-specific endodeoxyribonucleases were set out individually in subclasses EC 3.1.23 and EC 3.1.24 (since deleted), with 113 separate entries. These are now included in three entries EC, EC and EC A complete listing of all of these enzymes has been produced by R.J. Roberts and is available at

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