2. • Biological catalyst.
• Almost all enzymes are
protein.
• There are some nucleic
acids that behave like
enzymes. These are
called ribozymes.
Carbonic anhydrase
Ribozymes
HSE Zoology Blog 2
3. Inorganic catalysts
• Work efficiently at high
temperatures and high
pressures.
Enzyme catalysts
• Enzymes get damaged at
high temperatures (above
40°C).
Vanadium Pentoxide
HSE Zoology Blog 3
4. • Chemical compounds
undergo two types of
changes.
– Physical changes.
– Chemical changes
(Chemical reaction).
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5. • Change in shape without
breaking of bonds.
Ice
Water
Water
vapour
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6. • Bonds are broken and
new bonds are formed
during transformation.
Ba(OH)2 + H2SO4 → BaSO4 + 2H2O
• Starch → Glucose
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7. • Rate of a physical or
chemical process refers
to the amount of
product formed per unit
time.
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8. • In the absence of any
enzyme this reaction is
very slow.
• I.e. 200 molecules of
H2CO3/Hour.
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9. • By using the enzyme carbonic anhydrase, the reaction
speeds is 600,000 molecules /second.
• The enzyme has accelerated the reaction rate by
about 10 million times.
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10. • It is a metabolic activity in
which glucose becomes
pyruvic acid through ten
different enzyme catalysed
metabolic reactions.
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11. • Enzymes bring down
this energy barrier
making the
transition of
substrate to product
more easy.
HSE Zoology Blog 11
13. E + S → ES → EP → E + P
• The substrate binds to the active site of the enzyme, fitting into
the active site (E+S).
• The binding of the substrate induces the enzyme to alter its shape,
fitting more tightly around the substrate (ES).
• The active site of the enzyme, now in close proximity of the
substrate breaks the chemical bonds of the substrate and the new
enzyme- product complex (EP)is formed.
• The enzyme releases the products of the reaction (E+P) and the
free enzyme is ready to bind to another molecule of the substrate
and run through the catalytic cycle once again.
HSE Zoology Blog 13
16. • Each enzyme shows its
highest activity at a particular
temperature called the
optimum temperature.
• Enzyme activity declines both
below and above the
optimum value.
• Low temperature preserves
the enzyme in a temporarily
inactive state whereas high
temperature destroys
enzymatic activity because
proteins are denatured by
heat.
Optimum temperature
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17. • Each enzyme shows its
highest activity at a
particular pH called the
optimum pH.
• Enzyme activity declines
both below and above
the optimum value.
Optimum pH
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18. • With the increase in substrate
concentration, the velocity of
the enzymatic reaction rises
at first.
• The reaction ultimately
reaches a maximum velocity
(V max) which is not exceeded
by any further rise in
concentration of the substrate.
• This is because the enzyme
molecules are fewer than the
substrate molecules .
• After saturation of these
molecules, there are no free
enzyme molecules to bind
with the additional substrate
molecules.
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19. • The activity of an
enzyme is also sensitive
to the presence of
specific chemicals that
bind to the enzyme.
• Binding of the chemical
shuts off enzyme
activity –that chemical
is called inhibitor and
the process is called
inhibition.
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20. • When the inhibitor
closely resembles the
substrate in its
molecular structure and
inhibits the activity of
the enzyme, it is known
as competitive
inhibitor.
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21. • Due to its close structural
similarity with the substrate,
the inhibitor competes with
the substrate for the substrate
binding site of the enzyme.
• Consequently, the substrate
cannot bind and as a result,
the enzyme action declines.
• Inhibition of succinic
dehydrogenase by malonate
which closely resembles the
substrate succinate in
structure.
• Succinate Succinic dehydrogenase
Malonate
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23. • Enzymes are composed of
one or several
polypeptide
chains(Proteins).
• The non protein part of
the enzymes is called
cofactor, which make the
enzyme catalytically
active.
• The protein portion of the
enzymes is called the
apoenzyme.
Protein Non protein Holoenzyme
Apoenzyme Cofactor Holoenzyme
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25. • Organic compounds
• They are tightly bound
to the apoenzyme.
• In peroxidase and
catalase, which catalyze
the breakdown of
hydrogen peroxide to
water and oxygen,
haem is the prosthetic
group.
(Prosthetic group)
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26. • Organic compounds
• Their association with the
apoenzyme is only
transient, usually
occurring during the
course of catalysis.
• The essential chemical
component of many
coenzymes are vitamins,
e.g., coenzyme
nicotinamide adenine
dinucleotide (NAD) and
NADP contain the vitamin
niacin.
HSE Zoology Blog 26
27. • A number of enzymes
require metal ions for
their activity.
• Zinc is a cofactor for the
proteolytic enzyme
carboxypeptidase.
HSE Zoology Blog 27
28. Cofactor
Prosthetic group
Organic compounds.
They are tightly bound
to the apoenzyme.
In peroxidase and
catalase, which catalyze
the breakdown of
hydrogen peroxide to
water and oxygen, haem
is the prosthetic group.
Co enzymes
Organic compounds.
Their association with
the apoenzyme is only
transient, usually
occurring during the
course of catalysis.
The essential chemical
components of many
coenzymes are vitamins
coenzyme nicotinamide
adenine dinucleotide (NAD)
and NADP contain the
vitamin niacin.
Metal ions
A number of enzymes
require metal ions for
their activity
Zinc is a cofactor for
the proteolytic enzyme
carboxypeptidase.
HSE Zoology Blog 28
