Enzyme classification
73 likes52,866 views
This document discusses the classification and nomenclature of enzymes. It notes that enzymes are proteins that catalyze chemical reactions without being consumed. There are several ways enzymes can be named, including by the type of reaction they catalyze (using a suffix like -ase), their substrate, source, regulation, or randomly. The document then describes the systematic classification system developed by the International Union of Biochemists which groups enzymes into six major classes based on the type of reaction catalyzed and assigns each an Enzyme Commission (EC) number for identification.
Enzyme classification
- 1. Classification of enzymes Namrata Chhabra M.D. Biochemistry 15-May-20 Namrata Chhabra 1
- 2. • Biologic polymers that catalyze the chemical reactions • Enzymes are neither consumed nor permanently altered because of their participation in a reaction • Except for catalytic RNA molecules, or ribozymes, enzymes are proteins in nature. • In addition to being highly efficient, enzymes are also extremely selective catalysts. Enzymes- Introduction 15-May-20 Namrata Chhabra 2
- 3. Nomenclature of enzymes a) Based on the type of reaction catalyzed (followed by the suffix –ase) b) Based on the nature of substrate c) Based on the source of enzyme d) Based on its regulation e) Trival names 15-May-20 Namrata Chhabra 3
- 4. Nomenclature of enzymes Based on the type of reaction catalyzed (followed by the suffix –ase) • Dehydrogenase • Protease • Isomerase • Reductase • Transferase 15-May-20 Namrata Chhabra 4
- 5. Nomenclature of enzymes Based on the nature of substrate • Glucokinase • Hexokinase • Xanthine oxidase • Alcohol dehydrogenase 15-May-20 Namrata Chhabra 5
- 6. Nomenclature of enzymes Based on the source of enzyme • Pancreatic lipase • Gastric lipase • Salivary amylase • Muscle phosphorylase • Hepatic phosphorylase 15-May-20 Namrata Chhabra 6
- 7. Nomenclature of enzymes Based on its regulation • Hormone specific lipase Random names • Trypsin • Pepsin • Thrombin 15-May-20 Namrata Chhabra 7
- 8. Systematic Names of enzymes • The International Union of Biochemists (IUB) classification • Each enzyme has a unique name and code number that identifies the type of reaction catalyzed, and the substrates involved. • Enzymes are grouped into six classes. 15-May-20 Namrata Chhabra 8
- 9. Class-1- Oxidoreductases The oxidoreductases catalyze the transfer of reducing equivalents(hydrogen and electrons)from one redox system to another. Examples: Dehydrogenase, oxidase, oxygenase, hydro peroxidase • Lactate dehydrogenase • Alcohol dehydrogenase • Aldehyde dehydrogenase • Xanthine oxidase • Cytochrome oxidase 15-May-20 Namrata Chhabra 9
- 10. Reaction catalyzed by dehydrogenase 15-May-20 Namrata Chhabra 10
- 11. Class 2- Transferases The transferases catalyze the transfer of other groups from one molecule to another. Oxidoreductases and transferases generally require coenzymes. Examples: • Amino transferase • Glucosyl transferase • Methyl transferase • Phospho transferase 15-May-20 Namrata Chhabra 11
- 12. Reaction catalyzed by transferase 15-May-20 Namrata Chhabra 12
- 13. Class 3- Hydrolases The hydrolases cause cleavage of bond using water. Examples: • Protease • Peptidase • Glycosidase • Phosphatase 15-May-20 Namrata Chhabra 13
- 14. Reaction catalyzed by hydrolase 15-May-20 Namrata Chhabra 14
- 15. Class 4 Lyases • The Lyases catalyze reactions involving either the cleavage or formation of chemical bonds (also known as synthases) • with double bonds either arising or disappearing • Cleavage of bond does not require water. • Lyases usually break C-C, C-O, C-N, or C-S linkages. Examples: Fumarase, Arginosuccinase, glutamate decarboxylase 15-May-20 Namrata Chhabra 15
- 16. Reaction catalyzed by Lyase 15-May-20 Namrata Chhabra 16
- 17. Class 5- Isomerases • The isomerases move groups within a molecule, without changing the gross composition of the substrate. Examples: • Epimerase • Aldose ketose isomerase • Mutase 15-May-20 Namrata Chhabra 17
- 18. Reaction catalyzed by Isomerase 15-May-20 Namrata Chhabra 18
- 19. Class 6- Ligases • The ligation reactions catalyzed by ligases (“synthetases,” class 6) are energy-dependent and are therefore always coupled to the hydrolysis of nucleoside triphosphates. Examples: • DNA Ligase • Pyruvate carboxylase • Acetyl Co A carboxylase 15-May-20 Namrata Chhabra 19
- 20. Reaction catalyzed by Ligase 15-May-20 Namrata Chhabra 20
- 21. Enzyme Commission number (EC number) • Each enzyme is entered in the Enzyme Catalogue with a four-digit Enzyme Commission number (EC number). • The first digit indicates membership of one of the six major classes. The next two indicate subclasses and sub-subclasses. • The last digit indicates where the enzyme belongs in the sub-subclass. 15-May-20 Namrata Chhabra 21
- 22. Enzyme Commission number (EC number) • The IUB name of hexokinase is ATP:D-hexose 6-phosphotransferase E.C. 2.7.1.1. • This name identifies hexokinase as a member of class 2 (transferases), subclass 7 (transfer of a phosphoryl group), • sub-subclass 1 (alcohol is the phosphoryl acceptor), • and "hexose-6" indicates that the alcohol phosphorylated is on carbon six of a hexose. • However, it is still called as hexokinase. 15-May-20 Namrata Chhabra 22
- 23. 15-May-20 Namrata Chhabra 23
- 24. Thank you 15-May-20 Namrata Chhabra 24