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Classification of Enzyme, IUB classification


                            Classification of Enzymes

Enzymes are broadly of two types:

1.) Intracellular or Endoenzymes:-
They are functional within cells where they are synthesized.

2.)Extracellular or Exoenzymes:
These enzymes are active outside the cells.
Example: Digestive enzymes like Pepsin, Trypsin, Amylase.

Classification of Enzymes by IUB System,
Enzymes are classified by complex system, suggested by commission on enzymes of International Union of Biochemistry (IUB). Based on their action they are divided into 6 major classes. Each enzyme is assigned a 4 Digit code number.

(1)Oxido-Reductases:
Enzymes in this class are involved in Oxidation-Reduction reactions.
Example: Alcohol Dehydrogenase.

(2)Transferases:
Enzymes that catalyze transfer of Functional groups are called as Transferases.
Example: Phosphorylases

(3)Hydrolases:
These are enzymes that bring about hydrolysis of various compounds.
Example: Lipase

(4)Lyases:
Enzymes specialized in addition or removal of water.
Example: Aldolase

(5)Isomerases:
Enzymes involved in all isomerization reactions.
Example: Phosphotriose Isomerase.

(6)Ligases:
Enzymes catalyzing synthetic reactions where two molecules are joined together and ATP are used.
Example: Succinate thiokinase