This slide share is related to the "ENZYMES" and explains all the features of enzyme, characteristics, properties, types ,factors affecting, inhibitors, and functioning of enzymes. it is a great effort i hope u will get benefit.
2. Nimra Khan (Leader) Roll no. 34
Taqdees Fatima Roll no. 04
Iqra Dastgeer Roll no. 41
Kashmala Bibi Roll no. 06
Shaista Fatima Roll no. 44
Laiba Islam Roll no. 37
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. ModelsLock 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)
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
typesTransaminases
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