1. Presented by
Ashwin.A.S
Register No:PR12BT1005

2. ENZYME
A protein with catalytic properties due to its
power of specific activation

3. Enzyme structure
• Enzymes are proteins
• They have a globular
shape
• A complex 3-D structure
Pancreatic amylase

4. • substrate concentration
• pH
• temperature
• inhibitors
Factors affecting Enzymes

5. The effect of temperature
Temperature / °C
Enzyme
activity
0 10 20 30 40 50
Q10
Denaturation
Temperature
activation
Temperature
inactivation

6. • Q10 (the temperature coefficient) = the increase in
reaction rate with a 10°C rise in temperature.
• For chemical reactions the Q10 = 2 to 3
(the rate of the reaction doubles or triples with
every 10°C rise in temperature)
• Enzyme-controlled reactions follow this rule as
they are chemical reactions
• BUT at high temperatures proteins denature
The effect of temperature

7. • The optimum temperature for an enzyme
controlled reaction will be a balance between the
Q10 and denaturation.
• For most enzymes the optimum temperature is
about 30°C
• Many are a lot lower, cold water fish will die at
30°C because their enzymes denature
• A few bacteria have enzymes that can withstand
very high temperatures up to 100°C
• Most enzymes however are fully denatured at 70°C
Continued…

8. 1. Influence of temperature on the reaction rate constant
2. Thermal denature of the enzymes at the elevated
temperatures
Two factors considered while studying the effect of
temperature on the rate of enzyme catalyzed reaction

9. • Can reveal information about binding and release of
substrate and products
• At 100◦C few enzymes exhibit activity and at temperature
near freezing ,rates are very slow
• The study of enzyme reactions at low temperatures is called
cryoenzymology
– Study of individual steps in an enzymatic reaction using stopped flow
or other techniques
• Enzymes obtained from thermophiles show enhanced
thermal stability and operate at very high temperatures,
thermal denaturation results in an optimum temperature
for enzyme function
1. Temperature and rate enhancement

10. • The temperature range over which thermal denaturation
occurs varies with the nature of the enzyme considered
– Mammalian enzymes denaturation occurs at 45 to 55◦C as these
enzymes having optimum temperatures around 37◦C
• Thermal deactivation may be reversible or irreversible, and
depends on the temperature to which the enzyme is raised
and the period of time it is held at this temperature
• The events leading to thermal denaturation are generally
considered to involve an initial reversible denaturation
followed by an irreversible denaturation step
– Irreversible step is the result of polymolecular process such as
aggregation and precipitation; else conformational or covalent
changes may result in deactivation
2.Thermal deactivation of enzymes