enzymes name: chebet milton contact: [email protected]@yahoo.com subject:...
TRANSCRIPT
Learning objectives • Define enzymes• Classify enzymes• Describe the mode of enzyme action (lock and key
hypothesis)• Do the mouse mischief exercises at the end using
the given mice
Introduction to Enzymes
• What are enzymesbiological catalysts, protein in nature which speed up and control the rate of chemical reaction in living organisms
• Classification of enzymes– Intracellular enzymes.– Extracellular enzymes.
Enzyme Action
Learning objective: to describe different models forenzyme action and to investigate factors which control the rate of an enzyme reaction
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Lock and Key
Lock and Key
However certain substances can bind to the enzyme at sites other than theActive site and modify its activity (inhibitors/co-factors)
Idea that the enzyme is flexible
Induced Fit
Enzyme reactions
enzyme + substrate enzyme-substrate complex
Enzyme reactions
enzyme + substrate enzyme-substrate complex
E +S ES
Enzyme reactions
enzyme + productenzyme-substrate complex
E +PES
enzyme + substrate enzyme-substrate complex
E +S ES
Enzyme activity
How fast an enzyme is workingRate of Reaction
Enzyme activity
How fast an enzyme is workingRate 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
Variable you are looking at
Enzyme activity
Four Variables
Factors affecting Enzyme activity
Four Variables
Temperature
pH
Enzyme Concentration
Substrate Concentration
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Temperature
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Temperature
0 20 30 5010 40 60
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Temperature
0 20 30 5010 40 60
40oC - denatures
5- 40oC Increase in Activity
<5oC - inactive
Effect of heat on enzyme activityIf you heat the protein above its optimal temperature
bonds break meaning the protein loses it secondary and tertiary structure
Effect of heat on enzyme activity
Denaturing the protein
Effect of heat on enzyme activity
Denaturing the protein
ACTIVE SITE CHANGES SHAPE SO SUBSTRATE NO LONGER FITS
Even if temperature lowered – enzyme can’t regain its correct shape
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pH
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pH
1 3 42 5 6 7 8 9
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pH
1 3 42 5 6 7 8 9
Narrow pH optima
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pH
1 3 42 5 6 7 8 9
Narrow pH optima
WHY?
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pH
1 3 42 5 6 7 8 9
Narrow pH optima
Disrupt Ionic bonds - Structure
Effect charged residues at activesite
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Enzyme Concentration
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Enzyme Concentration
Enzyme Concentration
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Substrate Concentration
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Substrate Concentration
Substrate Concentration
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Substrate Concentration
Substrate Concentration
Active sites full- maximum turnover
In this mischief exercise your are required to Highlight a word in the green (right hand) column and drag it into a middle box corresponding
