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Published byGary Nichols Modified over 6 years ago
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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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Induced Fit
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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 ES E +P
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How fast an enzyme is working
Enzyme activity How fast an enzyme is working Rate of Reaction
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How fast an enzyme is working
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 Variable you are looking at
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Enzyme activity Four Variables
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Enzyme activity Temperature pH Enzyme Concentration
Four Variables Enzyme Concentration Substrate Concentration
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Temperature Rate of Reaction
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Temperature Rate of Reaction 10 20 30 40 50 60
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Temperature 5- 40oC Increase in Activity 40oC - denatures
Rate of Reaction 10 20 30 40 50 60 <5oC - 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 can’t regain its correct shape
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pH Rate of Reaction
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pH Rate of Reaction 1 2 3 4 5 6 7 8 9
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pH Narrow pH optima Rate of Reaction 1 2 3 4 5 6 7 8 9
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pH Narrow pH optima WHY? Rate of Reaction 1 2 3 4 5 6 7 8 9
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Affect charged atoms at active
pH Narrow pH optima Disrupt Ionic bonds - Structure Rate of Reaction Affect charged atoms at active site 1 2 3 4 5 6 7 8 9
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Enzyme Concentration Rate of Reaction
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Enzyme Concentration Rate of Reaction Enzyme Concentration
If substrate is available, rate of reaction will increase as enzyme concentration increases
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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 As substrate concentration increases, reaction rate will increase until All enzymes are working
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