Enzymes are classified into six functional classes by the International Union of Biochemists based on the type of reactions they catalyze. The six classes are: 1) oxidoreductases, 2) transferases, 3) hydrolases, 4) lyases, 5) isomerases, and 6) ligases. This classification system is known as the EC number classification.

1. Classification of enzyme
functional classes
Muhammad Nasir Iqbal
SP19-RBI-012

2. Enzymes Are Classified into six functional Classes (EC number Classification) by the
International Union of Biochemists (I.U.B.). on the Basis of the Types of Reactions
That They Catalyze
• EC 1. Oxidoreductases
• EC 2. Transferases
• EC 3. Hydrolases
• EC 4. Lyases
• EC 5. Isomerases
• EC 6. Ligases

18. References
• Nomenclature Committee of the International Union of Biochemistry and
Molecular Biology (NC-IUBMB) Classification and Nomenclature of Enzymes by
the Reactions they Catalyse http://www.enzyme-database.org/rules.php
• Lehninger, PRINCIPLES OF BIOCHEMISTRY Fourth Edition David L. Nelson
(University of Wisconsin–Madison) Michael M. Cox (University of Wisconsin–
Madison), Chapter 06
• Structural Biochemistry/Specific Enzymes and Catalytic Mechanisms/Enzyme
Classification
https://en.wikibooks.org/wiki/Structural_Biochemistry/Specific_Enzymes_and
_Catalytic_Mechanisms/Enzyme_Classification