Enzyme - Effects of Temperature and pH on Enzyme Activity and Deactivation.

2. The Biological Catalysts
Effect of Temperature and
pH
on Enzyme Deactivation
Topic of Presentation: Presented By:
Rahat Inayat Ali
14 CH 23

3.  As we know that , a Catalyst is a substance that
speeds up or alter the rate of a Chemical reaction,
but it is not itself changed by the reaction.
 Similarly, an Enzyme is a substance that speeds up
or alter the rate of a Biological reaction, but it is
not itself changed by the reaction.

4.  Proteins are long molecules that are folded into a specific shape.
catalase amylase trypsinpepsin

5. Active site:
Enzyme

6. Active site:
The site on the
enzyme where the
reaction occurs
Enzyme
Substrate molecules

7. Active site:
The site on the
enzyme where the
reaction occurs
Enzyme
Product molecules

8.  The lock and key hypothesis states that the active site specifically
matches the shape of the substrate molecule
enzyme
Each enzyme is specific to one substrate molecule
or type of molecule
active site

9.  At low temperatures enzyme controlled reactions go slowly
because the molecules have low kinetic energy.
The rate of an enzyme controlled reaction is
affected by temperature

10. But this only occurs up to the
optimum temperature
(usually about 40o
C)
The temperature at which
the rate of reaction is
fastest is known as the
optimum temperature
When temperature increases the reaction also
increases as the molecules have more kinetic energy

11. After the optimum temperature the heat causes
the enzyme to denature
 The enzyme changes shape and the active site no longer matches
the shape of the substrate molecule

12. Rate
Of
Reaction
Temperature/o
C
0 10 20 30 40 50 60 70
Optimum temperature
Enzyme
is denaturing
Rate of reaction of an enzyme reaction changes
at different temperatures
Molecules gain
kinetic energy

13.  Enzymes prefer to work at an optimum pH. Outside of its pH range
the enzyme is denatured.
Rate
Of
Reaction
pH
1 2 3 4 5 6 7 8 9 10 11 12
pepsin amylase
The activity and shape of enzymes is also
affected by pH
Optimum pH

14. www.google.com
www.wikipedia.com
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