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Enzymes
  Enzyme classes:
  EC 1: Oxidoreductases
  EC 2: Transferases
  EC 3: Hydrolases
  EC 4: Lyases
    EC 4.1
    EC 4.2
    EC 4.3
    EC 4.4
    EC 4.5
    EC 4.6
    EC 4.99
  EC 5: Isomerases
  EC 6: Ligases
  General information:
  Catalytic mechanism
  Enzyme kinetics
  Inhibitors
  Enzymes in industry

EC 4 Lyase, Nomenclature

Lyase definition and nomenclature

According to the NC-IUBMB (Nomenclature Committee of the International Union of Biochemistry and Molecular Biology) classification, EC 4 lyases are enzymes that catalyse Carbon-Carbon (C-C), Carbon-Oxygen (C-O), Carbon-Nitrogen (C-N) and other bond cleavage not via hydrolysis or oxidation. The nomenclature for systematic names is based on the standard scheme: substrate group-lyase. In common names an additional suffix -lase is used. If lyase remove water molecule, then the common name can be dehydratase. Because of all lyases can work as synthases, the classification is based on the most important direction of reaction and the name synthase can be used instead of lyase.

EC 4 number classification of Lyases

This classification is based on the chemical bond cleaved by enzymes.

EC 4.1 - Cleaved Carbon-Carbon chemical bond.
EC 4.2 - Cleaved Carbon-Oxygen chemical bond.
EC 4.3 - Cleaved Carbon-Nitrogen chemical bond.
EC 4.4 - Cleaved Carbon-Sulphur chemical bond, basically removing or substituting of H₂S group.
EC 4.5 - Cleaved Carbon-Halide chemical bond, HCl elimination.
EC 4.6 - Cleaved Phosphorous-Oxygen chemical bond.
EC 4.99 - All other Lyases. Temporary class for miscellaneous Lyases.