Enzymology properties & classsification
- 1. Enzymology: Properties & Classification Dr. Rohini C Sane
- 2. Enzymes Definition of enzyme: Biocatalysts synthesized by living cells Properties of Enzymes 1. Protein in nature (exception RNA ribosomes ) 2. Colloidal & thermo labile 3. Specific in action 4. Hydrolysis of enzymes (proteins ) With strong acids With Enzymes 100 ⁰ C 37 ⁰ C Require days for completion Require Hours for completion
- 3. Enzymes History of Enzymes : 1. 1876 Kuhne found enzyme in yeast 2.1883 Buchner yeast ( sugar alcohol ) Isolation of enzyme system from cell free extract of yeast ( Zymase ) 3.1926 :James Sumner Isolation & crystallization of urease 4.1930 : Northtop Crystallization of GIT enzymes
- 4. Nomenclature & classification of enzymes • I -Intracellular enzymes = nonfunctional plasma enzymes • II –Extracellular enzymes = functional plasma enzymes—DIGESTIVE ENZYMES IUB –International Union of Biochemistry enzyme commission 1961 Enzyme name = substrate + ase substrate E1 ↙ E2 ↓ ↘ E3 ↘ E4 Oxidation isomerization hydrolysis transfer E1,E2, E3,E4 DIFFERENT ENZYMES WITH SINGLE ENZYMES enzymes ↙ ↓ ↘ ↘ Substrate 1 Substrate 2 Substrate 3 Substrate 4 E SINGLE ENZYMES DIFFERENT NAMES
- 5. Classification of enzymes( IUB ) EC Enzyme code number 4 digits a) First digit main class type of reactions b) Second digit subclass type of group involved c) Third digit sub subclass type of substrate on which enzyme on which enzyme acts d) Forth digit individual enzyme systematic serial number & name Six Classes Of Enzymes 1. Oxido- reductases O 2. Transferases T 3. Hydrolases H 4. Lyases L 5. Isomerases I 6. Ligases L
- 6. Classification of enzymes 1.Oxido reductases: catalyze oxidation of one substrate with simultaneous reduction of another substrate EC 1.1.1.49 : G-6-P + NADP⁺ 6- Gluconolactone + NADPH+ H⁺ 2. Transferase :catalyze Transfer of one group ( other than H ) EC 2.7.1.1 : Hexose + ATP * Hexose -6-P +ADP (* Hexokinase ) 3. Hydrolase : catalyze hydrolysis of esters ,ethers ,peptides ,glycosides bonds by adding H2O & then breaking bonds EC 3.1.1.7 : Acetyl Choline + H2O * Choline + Acetate(*Acetyl Choline Esterase –Hydrolase )
- 7. Classification of enzymes 4. Lyases : remove groups from substrate or break bonds by mechanism other than hydrolysis EC 4.2.1.2 : F 1,6 biphosphate * GAP+ DHAP ( *ALDOLASE ) 5. Isomerases : produce optical, geometric isomers (racemase /epimerase/cis trans isomerase ) 6. ligases :ATP dependent condensation of two molecules Enzymes link substrate together usually with simultaneous hydrolysis of ATP A+ B +ATP AB + ADP + Pi • Glutamate + NH3 +ATP * Glutamine +ADP + Pi (* Glutamine Synthtase )
- 8. Classification of enzymes CLASS CATALYSIS TYPE OF REACTION EXAMPLE 1 Oxido reductases Transfer of hydrogen Oxidation reduction AH2 +B A+ BH2 2 Transferase Transfer of groups other than H A-X +B A+B-X 3 Hydrolases Cleave bond after adding H2O Hydrolysis A-B +H20 AH +BOH 4 Lyases Cleave without adding H2O Lysis A-B +X-Y AX +B-Y 5 Isomerases Intramolecular transfer isomerization (A A’ ) 6 Ligases ATP condensation of two molecules Ligation A+ B+ATP A-B +ADP +Pi Synthatses ATP dependent biosynthetic reactions Glutamine Synthtase Synthase : ATP independent biosynthetic reactions ALA -Synthase ,GLYCOGEN Synthase
- 9. 1.Oxido reductases REDUCTION Pyruvate + NADH Lactate + NAD⁺ ( Lactate Dehydrogenase ) ←←←← OXIDATION Pyruvate & Lactate ( REDOX PAIR) OXIDATION Succinate +FAD⁺ Fumarate + FADH +H( Succinate Dehydrogenase ) ←←←← REDUCTION
- 11. 2. Transferases : Serum Glutamate Oxaloacetate Transaminase(SGOT)
- 12. 2.Transferases : Serum Glutamate Pyruvate Transaminase (SGPT )
- 13. 3.HYDROLASES
- 15. 3.HYDROLASES
- 16. 4.LYASES
- 17. 4.ISOMERASES :
- 18. 6.Ligases
- 19. Naming of Enzyme ENZYME NAME: 4 DIGIT NUMBER + SYSTEMATIC NAME ATP + Glucose ADP + D- Glucose- 6- Phosphate 2.7.1.1 ATP Glucose Phosphotransferase 2 : Transferase (type of reaction) 1: Phospho transferase (type of group transferred ) 1 : Hydroxyl group as acceptor (acceptor group ) 1: Glucose as acceptor ( substrate ) TRIVIAL NAME :HEXOKINASE