A comprehensive presentation on Properties & Classification of Enzymes for MBBS ,BDS, B Pharm & Biotechnology students to facilitate self- study.

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

10. 1.Oxido reductases

11. 2. Transferases : Serum Glutamate Oxaloacetate Transaminase(SGOT)

12. 2.Transferases : Serum Glutamate Pyruvate Transaminase (SGPT )

13. 3.HYDROLASES

14. HYDROLASES : INVERTASE

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