Enzymes what are they

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Enzymes
Learning objective to examine what enzymes are
and describe how they work.
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What are they?
Enzymes
Why do we need them?
Name some examples ?
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Enzymes
Globular proteins that catalyse chemical
reactions in living organisms
Properties
4
Enzymes
Globular proteins that catalyse chemical
reactions in living organisms
Specific
Properties
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Enzymes
Globular proteins that catalyse chemical
reactions in living organisms
Specific
Properties
Increase rate of the reaction
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Enzymes
Globular proteins that catalyse chemical
reactions in living organisms
Specific
Properties
Increase rate of the reaction
Unchanged at the end of the reaction
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Enzymes
Globular proteins that catalyse chemical
reactions in living organisms
Specific
Properties
Increase rate of the reaction
Unchanged at the end of the reaction
Need them
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Enzymes
Globular proteins that catalyse chemical
reactions in living organisms
Specific
Properties
Increase rate of the reaction
Unchanged at the end of the reaction
Reactions too slow to maintain life
Need them
Cant increase temperatures/pressure in cells
(fatal)
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Enzymes Are Proteins
The enzyme binds to the substrates by its active
site The active site is a pocket formed by the
folding of the protein where the substrates bind.
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Enzymes Are Proteins
The enzyme binds to the substrates by its active
site The active site is a pocket formed by the
folding of the protein where the substrates bind.
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How do enzymes work?
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An Example (in your blood)
CO2 H2O
Carbonic acid
H2CO3
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An Example (in your blood)
CO2 H2O
Carbonic acid
H2CO3
Product
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For a reaction to occur the CO2 and water would
have to collide with enough energy to break and
form bonds
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For a reaction to occur the CO2 and water would
have to collide with enough energy to break and
form bonds This is the activation energy
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CO2 H2O
Carbonic acid

Substrates
Product
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Energy
Progress of reaction
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Energy
Substrates
Progress of reaction
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Energy
Substrates
Product
Progress of reaction
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High energy intermediate
Energy
Substrates
Product
Progress of reaction
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High energy intermediate
Activation energy
Energy
Substrates
Product
Progress of reaction
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The minimum amount of energy needed to start the
reaction The Activation energy
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High energy intermediate
Activation energy
Enzymes reduce the height of the energy barrier
Energy
Substrates
Product
Progress of reaction
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Enzyme involved carbonic anhydrase Importance
The reaction without the enzyme is so slow that
CO2 would build up faster than it can be removed
from the blood poisons us. Speed 10,000,000
times faster with enzyme!
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Enzyme Action
Learning objective to describe different models
for enzyme action and to investigate factors
which control the rate of an enzyme reaction
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Lock and Key
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(No Transcript)
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Enzyme reactions
enzyme substrate
enzyme-substrate complex
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Enzyme reactions
enzyme substrate
enzyme-substrate complex
E S
ES
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Enzyme reactions
enzyme substrate
enzyme-substrate complex
E S
ES
enzyme product
enzyme-substrate complex
E P
ES
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Lock and Key
Problems Sometimes other substances can bind to
the enzyme at the active site or at sites other
than the Active site and modify its activity
(inhibitors/co-factors)
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Enzyme activity
How fast an enzyme is working Rate of Reaction
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Enzyme activity
How fast an enzyme is working Rate of Reaction
Rate of Reaction Amount of substrate changed
(or amount product formed) in a given period
of time.
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Enzyme activity
Rate of reaction
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Enzyme activity
Four Variables
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Enzyme activity
Temperature
pH
Four Variables
Enzyme Concentration
Substrate Concentration
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Temperature
Rate of Reaction
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Temperature
Rate of Reaction
0
20
30
50
10
40
60
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Temperature
5- 40oC Increase in Activity
40oC - denatures
Rate of Reaction
0
20
30
50
10
40
60
lt5oC - inactive
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Effect of heat on enzyme activty
If you heat the protein above its optimal
temperature bonds break meaning the protein
loses it secondary and tertiary structure
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Effect of heat on enzyme activty
Denaturing the protein
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Effect of heat on enzyme activty
Denaturing the protein
ACTIVE SITE CHANGES SHAPE SO SUBSTRATE NO LONGER
FITS
Even if temperature lowered enzyme cant regain
its correct shape
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Heat and pH are biggest factors. Importance
blood pH and fever

• 70 alcohol solution disinfectant
• Penetrates bacterial cell wall and denature
  proteins and enzymes inside cell.

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pH
Rate of Reaction
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pH
Rate of Reaction
A
1
3
4
2
5
6
7
8
9
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pH
Narrow pH range
Rate of Reaction
1
3
4
2
5
6
7
8
9
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pH
Narrow pH range
WHY?
Rate of Reaction
1
3
4
2
5
6
7
8
9
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pH
Narrow pH optimal range
Disrupt Ionic bonds - Structure
Rate of Reaction
Effect charged elements at Active site
B
1
3
4
2
5
6
7
8
9
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Enzyme Concentration
Rate of Reaction
50
Enzyme Concentration
Rate of Reaction
Enzyme Concentration
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Substrate Concentration
Rate of Reaction
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Substrate Concentration
Rate of Reaction
Substrate Concentration
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Substrate Concentration
Active sites full- maximum turnover
Rate of Reaction
Substrate Concentration