Suitable for elementary students of the subject. Best Wishes

1. Enzyme
by
Dr. Chandrajiit Singh
Food Scientist
Krishi Vigyan Kendra-Rewa (MP)
Mobile: 09893064376
E-mail: chandar30@gmail.com

2. Introduction of Enzyme
• Enzyme in Greek means ‘In Yeast’
• Yeast cells were the first to reveal enzyme activity in living organism.
• Hence the name ‘Enzyme’ was given.
Historical Evidence in Activities such as :
• Cheese preparation.
• Leavening of Bread.
• Vinegar Preparation.
• Wine Preparation.

3. History of Enzyme
SNo. Year Scientist’s
Name
Contribution
1. Historic Bacchus
(Greek)
First recognized use of enzyme for fermentation in
wine preparation.
2. 1827 Berzelius Defined and Recognized the nature of catalyst.
Identified ‘Ferments’ as catalysts produced by living
cells.
3. 1877 W. Kuhne Proposed the term Enzyme
4. 1894 Emil
Fischer
Demonstrated the specificity of enzymes and the
lock and key relationship between enzyme and
substrate.
5. 1913 Michaelis
and Menten
Developed kinetic theory of enzyme action.
6. 1926 J.B. Sumner First crystallized and enzyme, Urease and proved it
to be a protein.
7. 1946 J.B. Sumner Received Noble Prize for his work.

4. Definition
Enzymes are macro molecular biological catalyst which :
• Alters the rate of reaction (Increases or Decreases)
• Do not change itself.
• Specific in action.
• Protein in nature.

5. Few More Definitions
Substrate :
The molecules at the beginning of the process upon which enzymes may act
are called Substrate.
Product :
The molecule formed at the end of the reaction is known as Product.
Enzymology:
The branch of science which deals with the study of enzymes is known as
Enzymology.

6. Nomenclature of Enzyme
1. Substrate + ase (Suffix) = Name of Enzyme
Example:
• Urea + ase = Urease
• Arginine + ase = Arginase
• Tyrosine + ase = Tyrosinase
• Amylose + ase = Amylase
• Uric Acid +Uricase

7. Nomenclature of Enzyme
2. Group of Enzymes catalyzing similar reactions:
• Dehydrogenases
• Oxidase
• Poteinase.
• Lipase
• Glycosidase
• Decarboxylases

8. Nomenclature of Enzyme
3.Breaking down the substrate:
Substrate + lytic (Suffix) = Name of Enzyme
‘Lytic’ means break down.
Example:
• Proteolytic – Protein slitting.
• Sucrolytic – Sucrose splitting
• Lipolytic – Lipid (fat) splitting

9. Nomenclature of Enzyme
4. Few enzymes retain old traditional names:
Example:
• Pepsin
• Typsin
• Ptyalin
• Renin

10. Nomenclature of Enzyme
5.. Some proteinases from plant and microorganisms are named after the
species of origin:
Example:
• Pepain – From Papaya
• Ficin – Ficus
• Subtilisin – Bascillus subtilis

11. Classfication of Enzyme
Enzymes are classified as follows :
1. Oxidoreductases: Catalyses biological oxidation and reduction reactions.
Eg.: In respiration and fermentation process.
Important sub-classes are:
Dehydrogenases:
Electron transfer is accompanied with hydrogen ion transfer.
Eg: Alcohol dehydrogenase and Glutamic dehydrogenase in Animal Liver.
Oxidases :
Molecular oxygen is one of the reactants.
Eg: Cytochrome oxidase.

12. Classfication of Enzyme
Peroxidases:
H2O2 acts as oxidant.
Eg: Alcohol dehydrogenase and Glutamic dehydrogenase in Animal Liver.
Oxygenases:
Double Bond in the substrate is replaced by molecular oxygen.

13. Classification of Enzyme
2. Hydrolases:
Catalyzed hydrolytic reactions. These are as follows:
Proteases: (Proteolytic enzyme) : Attack peptide bonds
These are of two types:
 Proteinase- Endo-peptidase
 Peptidase- Exo-peptidase
Peptidase- Exo-peptidase :
Acts on peptide bonds adjacent to free amino or carboxyl group.
Types of Peptidases are: In the next slide …..

14. Classification of Enzyme
Types of Peptidases are:
Carboxypeptidases:
Acts on the peptide bond adjacent to free carboxyl group and liberates amino
acid.
Aminopeptidases:
Acts on the peptide bond adjacent to free amino group of the simple peptide.
Dipeptidases:
It acts on specific dipeptides
Eg.: Glycylglyci (i.e. Dipeptidase) which requires CO2+
or Mn2+.

15. Classification of Enzyme
Proteinase- Endo-peptidase :
Acts on interior peptide bonds of proteins however they also can act on
simple peptide and its derivatives.
Eg: Pepsin, Renin, Trypsin, Chymotrypsin and plasmin from animals.
Animal Proteinases:
Cathepsins – Intercellular proteinases found in most of animal tissues.
Richest sources are liver, kidney and spleen.
Plant Proteinases:
 Papain from unripe fruit of papaya,
 Bromelin found in pineapple,
 Ficin in the milky sap of Fig tree.

16. Factors Affecting Enzyme Activity
• Inhibitors :
Molecules that decrease enzyme activity is known as Inhibitor.
• Activators :
• Molecules that increase enzyme activity.
• Temperature:
Optimal temperature supports enzymatic activity.
• Hydrogen Ion Concentration (pH) :
Optimal pH supports enzymatic activity.

17. Structure of Enzyme
• Enzymes are generally globular proteins, acting alone or in larger
complexes.
• Enzymes are linear chains of amino acids that fold to produce a three
dimensional structure.
• Sequence of the amino acids specifies the structure.
• Structure of enzyme determines the catalytic activity of the enzyme
(But this may not be the only factor).
• High temperature may denature the enzyme (Enzyme unfolds) and
hence deactivates it.

18. History of Biochemistry
• Hans Kreb – Proposed the Kreb cycle of the TCA in 1937.
• Embden & Mayerhoff – described the glycolytic pathway in
1925.
• James Watson & Francis Crick – described the double helical
structure of DNA in 1953

19. Lock and Key Model of the Catalytic Site
Courtesy: Text Book of Biochemistry By A.K. Berry

20. Enzymes in Digestion
• Enzymes break down large insoluble molecules (e.g. starch,
proteins and fats) into small soluble molecules.
• Small soluble molecules can be absorbed into the blood from
the small intestines.

21. Lock and Key Model
In 1894 Emil Fisher proposed the model.
The model proposes that :
• Both the enzyme and the substrate possess specific
complementary geometric shapes.
• Shapes of enzyme and substrate fit exactly into one another.
• This model explains enzyme specificity.
• But this model fails to explain the stabilization of the
transition state that enzymes achieve.

22. Enzymes in Digestive System of Human Being
Courtesy: Study Material for the Course, Department of Biochemistry, College of
Agriculture, Rajendranagar, Hyderabad

23. Uses of Enzymes
At Home :
• Enzymes can be taken out of organisms, purified and then used in
science and industry.
• Biological washing powder contains amylase, lipases and
proteases.
• They break down any stains that contain carbohydrate, fat and
protein.
• Enzymes work at a low temperature and saves electricity and
makes them good for delicate fabrics.
• Some people, however, are allergic to the enzymes and suffer skin
problems.

24. Induced Fit Model of the Interaction of Substrate and Enzyme

25. Enzyme Accelerates Catalysis by Reducing
Required Energy of Activation

26. Mirchaelis-Menten Costant

27. Effect of Temperature on the Rate of Enzyme Activity

28. Influence of Acidity (pH) on Enzyme Action

29. Effect of Substrate Concentration on Rate of Reaction with
Constant Amount of Enzyme Present

30. Effect of Enzyme Concentration on Rate of Reaction with
Substrate Available in Excess

31. Thank You