Classification of enzyme

Classification of enzyme

Classification of enzyme

Classification of enzyme:

Classification of the enzyme is very important to study about Enzymes and their reaction. The Enzymes are classified according to the reaction they catalyze. The classification is shown below:

  • Oxidoreductase:

Oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule to another molecule. The transfer of electron means the transfer of hydride of a hydrogen atom.


Classification of enzyme
  • Transferases:

Transferases are enzymes that catalyze the transfer of a functional group from a donor molecule to an acceptor molecule. Here Group transfer reactions are occurred.


  • Hydrolases:

Hydrolases are a class of enzymes that catalyze the hydrolysis of a chemical bond.

For example, an enzyme that catalyzed the following reaction is a hydrolase:

A–B + H2O → A–OH + B–H.

  • Lyase:

Lyase is an enzyme that catalyzes the breaking (an “elimination” reaction) of various chemical bonds by means other than hydrolysis and oxidation, often forming a new double bond or a new ring structure.

  • Example:
  • Ligase:

    Ligase is an enzyme that can catalyze the joining of two large molecules by forming a new chemical bond (Formation of C─C, C─S, C─O, and C─N bonds by condensation reactions coupled to ATP cleavage).

  • Example:
  • Isomerases:

    Isomerases are enzymes that catalyze the isomerization of a molecule. In other words, they facilitate the transfer of specific functional groups

  • Example:

Enzymes are classified according to the type of reaction they catalyze:

Classification of Enzymes

Class Reaction catalyzed Example Reactions
Oxidoreductases Oxidation-reduction Lactate dehydrogenase
Transferases Transfer groups of atoms Alanine transferase
Hydrolases Hydrolysis Sucrase
Lyases Add atoms/remove atom to/from a double bond Pyruvate decarboxylate
Isomerases Rearrange atoms Maleate isomerase
Ligases Use ATP to combine molecules Acetyl-Co A synthetase

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