The document provides an overview of enzymes, including their definition, models (lock and key, induced fit), chemical nature, classification, and mechanisms of action. It discusses factors affecting enzyme activity such as substrate concentration, temperature, and pH, along with inhibitors and related diseases. Additionally, it highlights the industrial applications of enzymes in various sectors including food, agriculture, and pharmaceuticals.

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2. Nimra Khan (Leader) Roll no. 34
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GROUP-V
Group Members

3. Introduction
 Lock and Key Model
 Induced Fit Model
 Chemical Nature of Enzymes
 Coenzymes and their actions
TOPIC Content
“ENZYMES”
CLASSIFICATION
 Mechanism
 Factors affecting
 Inhibitors
 Diseases
 Functions

4. What are enzymes?
Enzymes are the complex protein molecules and
catalyze reactions in living cells.They can increase the
efficiency of biochemical reaction .
OR
A catalyst reagent that increase the velocity of chemical
reactions of other substances without being destroyed
itself.

5. ModelsLock and Key Model
Induced Fit model
Lock & key model
Proposed by Fisher
Active site is rigid
Substrate have fixed shape
No change in enzyme shape

6. Induced fit model
Proposed by Koshland
Active sites are not rigid
Enzymes changes its shape of active site

7. Characteristics
All enzymes are globular proteins
Increase rate of reaction
Do not effect nature & properties of product
Small amount of enzyme can accelerate chemical
reaction
Some enzymes require cofactor for their composition
Lower the activation energy of reaction

8. Chemical nature of enzymes
Globular proteins
Cofactor non protein part
Specific for enzyme
 Cu2+ cytochrome oxidase
 K+ pyruvate kinase
 Mg2+hexokinase, pyruvate
kinase
 Ni2+ urease
Coenzyme non protein part necessary for
functioning of enzymes
Prosthetic group attached to apoenzyme
Apoenzyme  protein part
Halo enzyme

9. Coenzyme and its actions
i)NAD+ ii)NADP+
 Just have addition of 1 phosphate
in NADH+
 NADH+for ATP synthesis
 NADPH+for reduction of fatty
acids chlestrol
nicotinamide adenine dinucleotide (Nicotinamide Adenine
Dinucleotide Phosphate)

10. iii)FAD
(Flavin adenine dinucleotide)
iv)FMN
 Reacts same as FAD
 Exist in oxidized and reduced form
FMN +2H+ + eFMNH2
(Flavin mono nucleaotide)

11. Classification of enzymes
Enzyme are
classified
on following
basis
 Oxidoreductases-oxidation-reduction reactions
Phosphate dehydrogenases
 Transferases:- transfer of functional groups
Methyltransferases, Carboxyltransferases
 Hydrolases: hydrolysis reactions
Carboxylic ester hydrolyses
 Isomerases : isomerization reactions
Epimerases
 Lyases : addition to double bonds
Carboxy lyases, Aldehyde lyases
 Ligases: formation of bonds with ATP cleavage
Amino acid-RNA ligases

12. Oxygenase
Dehydrogenases
Hydroperoxides
1)Oxidoreductase
Oxidases involving donation of a hydrogen
atom, oxygen is reduced to water
(H2O) or hydrogen peroxide
(H2O2)
removing hydrogen atoms
[H] instead of oxygen [O] in
its oxido-reduction
reactions
Pyruvic acid-->lactic acid
Catalyzes the
decomposition of H2O2
H2O2+ +2H+ +2e--> 2H2O
Catalyze the incorporation of
molecular oxygen into the
substrate

13. 2)Transferases
 One acts as donor & other as acceptor
 Such as amino, acyl, methyl
typesTransaminases
amino acid become keto acid & keto acid as amino acid
Phosphotransferases
Transfer of phosphate group
Glucose +ATP--> Glucose 6-phosphate +ADP
Trans methylases
Transfer of methyl group
 Transpeptidases
transfer of amino acids or peptides
e.g: benzoyl-CoA + glycine--> hippuric acid +CoA-SH
 Transfer of functional group

14. Hydrolyses
Proteinases Carbohydrase's Lipid hydrolyzing
enzyme
Deaminases Deamidases
 Endopeptidases
 Exopeptidases
Catalyze the hydrolysis of
glyosidic bond
amylase starch
Affect the hydrolysis at
particular amino acid residue
Lipase Cholesterol
esterase
phospholipases
Adenase & guanase
Catalyze the
hydrolysis of
amides
aminopolypeptidases carboxypolypeptides
 Occur in intestinal juice
 Attack the protein molecule
containing free amino group
 In pancreatic juice
 Attack the polypeptide having free
carboxlic group

15. 4)Lyases
 Catalyze the addition of NH3, H2O & CO2
to double bond
5) Isomerases
 Catalyze structural changes within single molecule by
transfer of groups
 E.g: Glucose 6-phosphate --> fructose 6-phosphate
6)Ligases
 Enzyme catalyze condensation reactions
joining two molecules by forming 2 molecule
forming C-O,C-S,C-N

16. Activation Energy
• Any reaction doesn’t proceeds directly to product
formation
• There is always a transition state between ground
state and product
• Activation energy: The difference between the
energy levels of the ground state and the transition
state
• The function of a catalyst is to increase the rate of a
reaction, it does not affect reaction equilibrium
• So enzymes just lowers the activation energy

17. Factors affecting enzyme activity
Concentration of substrate
Temperature
Effect of pH
Enzymes concentration

18. Concentration of substrate
The frequency with which molecules collide is directly proportionate
to their concentrations
Concentration of enzymes
• Reaction velocity is directly proportional
to concentration of enzyme
• Serum enzyme for diagnosis of disease
-known volume of serum and
substrate taken at optimum pH and
temperature
-Enzymes is assayed in laboratory

19. Effect of temperature
• Velocity of an enzyme reaction increase with the increase in
temperature and then declines
• Increase in temperature cause increase in kinetic energy of
molecules
• A bell- shaped curved is obtained in graph
• Increase in enzyme velocity when temperature is increased by 10C
• Optimum temp for more enzymes id 40-45
• More then 50C enzymes denatured
Effect of pH
• Most intra cellular enzymes exhibits optimal activity at pH values
between 6-8
• Balance between enzyme denaturation at high or low pH and effects
on the charged state of enzyme, the substrate or both
• Exception- pepsin(1-2),acid phosphate (4-5),alkaline
phosphatase(10-11)

20. Inhibitors
A substance which can
react with enzyme in place
of substrate and can block
the active site called the
inhibitors.
Main types are two
Reversible inhibitors
Irreversible inhibitors

21. Reversible inhibition
 Inhibitors binds to enzyme through non-covalent bond
 Enzyme-inhibitor(EI) complex are formed
 Reversible by increasing substrate concentration
 No permanent effect on enzyme
Types
Competitive inhibitors
 Uncompetitive inhibitors
Non- competitive inhibitors

22. Competitive inhibitors
 Structural resemblance
 Formation of enzyme-substrate
complex reduce
 e.g: malonic acid & succinic acid
Non-competitive inhibitors
 No structural resemblance
 Inhibitor not combine with active site
 Combine at another place
 Change shape of enzyme

23. uncompetitive inhibitor
 Dose not combine with the free enzyme
 Combines only ES complex
 Usually seen in enzymes reactions in which two or more substances
are involved
Produce drugs to treat poisoning by methanol
Irreversible inhibitor
 Strong covalent bonds are produce b/w enzyme & inhibitor
 -SH groups can be irreversibly inhibitor by heavy metal ions such Hg2+,
Cu2+, or Ag2+
 e.g –SH + Ag+-->enzymes-S-Ag+H+

24. Diseases
PRPP synthase
 Phosphoribosyl pyrophosphate
 Ribose 5 –phosphate +ATP-->PRPP+ AMP
 Cause overproduction of uric acid &arthritis
 Pyrimidine 5-nucleaotide
 Developmental delay
 Seizures, ataxia(nervous disorder), language
defect
 &-ALAsynthesis
 Aminolaevulinic acid
 Over production & accumulation of heme precursors
 Produce porphyria

25. FUNCTIONS
 Amylase break down starch
 Protease breakdown protein into amino acids
 Lipase breakdown lipids into glycerol
 Chemical reaction at normal temperature
 food industry
 agriculture
 cosmetics
 pharmaceutical industry
Industrial uses
 speed up reaction
 cheese making
 brewing beer
 Baking bread