Lyases, nomenclature

EC nomenclature for enzymes A classification of ENZYMES according to the Enzyme Commission of the International Union of Biochemistry and Molecular Biology. Enzymes are allocated four numbers, the first of which defines the type of reaction catalyzed the next two define the substrates, and the fourth is a catalogue number. Categories of enzymes are EC 1, oxidoreduc-tases EC 2, transferases EC 3, hydrolases EC 4, lyases EC 5, isomerases EC 6, ligases (Synthetases). 

The addition of water to carbon-carbon double bonds is a reaction that is catalyzed by lyases belonging to the subclass of the hydro-lyases (E.C. 4.2.1.-), which have been grouped under the carbon-oxygen lyases. Not all members of this subgroup are capable of water addition to carbon-carbon double bonds. Nitrile hydratase (E. C. 4.2.1.84, discussed in Section 12.1) for instance, is categorized in this subclass and catalyzes the addition of water to nitriles. The nomenclature of the hydro-lyases subgroup, which contains hydratases and dehydratases, does not preclude any direction of the reaction, but rather reflects the context in which the enzyme was originally discovered. 

Note There is a systematic nomenclature for classifying the enzymes by function, as follows oxidoreductases involve oxidation-reduction reactions transferases involve the transfer of functional groups hydrolases involve hydrolysis reactions with water lyases involve the elimination of a group to form double bonds isomerases involve isomerization to a different structure but with the same chemical composition ligases involve the formation of a chemical bond simultaneously with ATP hydrolysis. There are in turn subclasses and sub-subclasses, and a subclass that... 

Enzymes are most frequently named by using the common system of nomenclature. The names are useful because they are often derived from the name of the substrate and/or the reaction of the substrate that is catalyzed by the enzyme. Enzymes are classified according to fimction. The six general classes are oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases. 

Enzyme commission of the International Union of Biochemistry and Molecular Biology (lUBMB) established two enzyme nomenclatures systematic and trivial. According the systematic nomenclature all enzymes are divided upon 6 classes l.Oxidoreductases 2. Transferases 3. Hydrolyses 4. Lyases cleaving C-C C-O, C-N bonds 5. Isomerases, and 6. indication ofbond formed. 

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