Presentation of enzymes

1. ENZYMOLOGY
KEHKASHAN SABIR
(LECTURER)

2. ENZYMOLOGY
• Enzymology is a field of study that deals with a specific group of proteins called
enzymes..
• It is the branch of biochemistry aiming to understand how enzymes work through
the relationship between structure and function.
• Enzymology is a multidisciplinary research field and integrates areas of
biochemistry, microbiology, molecular biology and genetics.

3. ENZYMES
• Enzymes are proteins that act as biological catalysts by accelerating chemical
reactions.
• Enzymes speed up a reaction without becoming part of the reaction but
themselves cannot initiate any chemical reaction.
• Almost all metabolic processes in the cell need enzyme catalysis in order to
occur at rates fast enough to sustain life.
• Enzymes are known to catalyze more than 5,000 biochemical reaction types.

4. ENZYMES
• The molecules upon which enzymes may act are called substrates.
• The enzyme combined with the substrate at a specific site known as the active
site.
• They form an Enzyme-Substance Complex (ES) which is broken or changed
• to give the Product (P).
• The enzyme converts the substrates into different molecules known as products.

5. ENZYMES

6. ACTIVATOR, INHIBITOR
• Like all catalysts, enzymes increase the reaction rate by lowering its activation
energy.
• Some enzymes can make their conversion of substrate to product occur many
millions of times faster.
• Enzyme activity can be affected by other molecules: inhibitors, activators.
• Molecules that decrease the enzyme activity are called inhibitors.

8. CO ENZYMES
• Molecules that increase the enzyme activity are called activators.
• An organic molecule that binds to the active sites of certain enzymes to assist in
the catalysis of a reaction is called co - enzyme.
• Coenzyme usually function as intermediate carriers of functional groups of
specific atoms or of electrons.
• Where the coenzyme is tightly bond to the enzyme molecule, it is usually called a
prosthetic group.

9. ISOZYMES
• There are enzymes that differ in amino acid sequence but they catalyze the same
chemical reaction and are called isozymes.

10. POINT TO REMEMBER
ALL ENZYMES ARE CATALYSTS BUT
……….
ALL CATALYSTS ARE NOT ENZYMES

11. NOMENCLATURE
• There are two naming systems for enzymes.
1. Trivial Naming:
• Gives no idea of source, function or reaction catalyzed by the enzyme.
• Example: trypsin, thrombin, pepsin.

12. NOMENCLATURE
2. Systematic Naming
• According to the International union Of Biochemistry an enzyme name has two
parts:
• First part is the name of the substrates for the enzyme.
• Second part is the type of reaction catalyzed by the enzyme. This part ends with
the suffix “ase”.
• Example: Lactate dehydrogenase

13. FACTORS EFFECTING ENZYMATIC
REACTIONS
• The following factors effect the enzymatic reactions
1. pH
2. Substrate concentration.
3. Temperature.

14. FACTORS EFFECTING ENZYMATIC
REACTIONS
1. pH
• Each and every enzyme is characterized by an optimum pH .
• At this specific pH level, a particular enzyme catalyzes the reaction at the fastest
rate than at any other pH level.
• For example, the enzyme pepsin is most active at an acidic pH, whereas the
enzyme trypsin performs best at a slightly alkaline pH.

15. FACTORS EFFECTING ENZYMATIC
REACTIONS

16. FACTORS EFFECTING ENZYMATIC
REACTIONS
2. Substrate concentration
• Greater the substrate so greater is the rate of reaction.
• More substrate so there is more frequent collision with enzyme.
• So reaction rate is high all active side of enzymes are occupied.
• Saturation level.

18. FACTORS EFFECTING ENZYMATIC
REACTIONS
3. Temperature
• If temperature is reduced to near or below freezing point, enzymes are
inactivated only, not denatured
• As the temperature increase, the kinetic energy of the substrate and enzyme
molecules increases and so they move faster. And the greater the rate of reaction.
• As the temperature increases further, the breakage of the hydrogen bonds and
other strong forces occurs .

19. FACTORS EFFECTING ENZYMATIC
REACTIONS
• So the shape of the active site altered and no longer fit the substrate.
• The enzyme is said to be denatured and loses its catalytic activity forever.

20. FACTORS EFFECTING ENZYMATIC
REACTIONS

21. CLASSIFICATION OF ENZYMES
• According to the International Union of Biochemists (I U B), enzymes are
divided into six functional classes.
• They are classified based on the type of reaction in which they are used to
catalyze.
• The six kinds of enzymes are:
• Hydrolases, oxidoreductases, lyases, transferases, ligases and isomerases.

22. CLASSIFICATION OF ENZYMES
1. Oxidoreductase
• Enzyme that catalyzes the transfer of electron from one electron the reductant to
another molecule the oxidant.
• We can simply say that these enzymes catalyze the oxidation and reduction
reactions.
• Example: Oxidases and dehydrogenases.

23. CLASSIFICATION OF ENZYMES
• Oxidase
• An enzyme which promotes the transfer of a hydrogen atom from a particular
substrate to an oxygen molecule, forming water.
• Dehydrogenase
• Enzyme that help in the removal of hydrogen.

24. CLASSIFICATION OF ENZYMES
2. Transferase
• An enzyme that help in the transfer of specific functional group from one
molecule to another molecule.
• Example: Kinase helps in the phosphorylation of a molecule.
• Transaminase: Catalyzing transfer of amino group between an amino acid and a
keto acid.

25. CLASSIFICATION OF ENZYMES
3. Hydrolase
• These enzymes catalyze the breakdown or hydrolysis of a compound using water.
• In this process energy is released.
• Example: Amylase catalyzes the hydrolysis of carbohydrates.
• Protease catalyzes the hydrolysis of proteins.

26. CLASSIFICATION OF ENZYMES
4. Lyase
• These enzymes catalyze the breaking of various chemical bonds by means other then
hydrolysis and oxidation.
• Example: Decarboxylase catalyzed the removal of carboxyl group in the form of CO2.
5. Isomerase
• They convert the molecule from one isomers to another. It facilitate the intramolecular
rearrangement in which bonds are broken and formed.

27. CLASSIFICATION OF ENZYMES
• Example: gluco-isomerase catalyze the isomerism of glucose to fructose.
6. Ligase
• They are also synthetase.
• They catalyze the formation of different bonds by the combination of two
compounds.
• It is a condensation reaction and uses ATP. Example: DNA ligase & DNA
polymerase etc.