Enzyme Inhibition

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  • Created by: Lotto65
  • Created on: 17-03-17 17:49
What are enzyme inhibitors?
Chemical substances
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What do enzyme inhibitors do?
Reduce the activity of an enzyme or prevent it completely
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Name two main types of inhibitor
Competitive and non-competitive
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How does competitive inhibition work?
The substrate and inhibitor are chemically similar. The inhibitor binds to the active site of the enzyme. This prevents the substrate entering the active site and binding so activity of enzyme is prevented
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How long before the enzyme will resume work with competitive inhibition?
Until the inhibitor dissociates
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What does 'dissociate' mean?
To withdraw and be released
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What sort of concentration of enzyme inhibitor can be added to prevent enzyme function?
Low (fixed) concentrations
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What happens to the effectiveness of the competitive inhibitor as the substrate concentration increases?
It decreases until it becomes negligible
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What is a competitive inhibitor and a substrate competing for?
The active site of an enzyme
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If the substrate binds to the active site, can the inhibitor bind too?
No
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Why does inhibitor effectiveness decrease as substrate concentration increases?
Greater chance of a substrate binding to an active site rather than an inhibitor
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How does non-competitive inhibition work?
The substrate and inhibitor are not similar. The inhibitor binds to a site on the enzyme that is not the active site. This changes the conformation of the enzyme, leading the substrate to no longer fit in the active site.
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What if the substrate can still fit in the active site of an inhibited enzyme?
It will not catalyse a reaction of it will happen at a slower rate
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If you have low fixed concentration of non-competitive inhibitor, does the substrate concentration make a difference to enzyme activity?
No - it will be inhibited at all substrate concentrations providing the percentage reduction of substrate is the same at all concentrations
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Why does substrate concentration not affect enzyme activity?
The substrate and non-competitive inhibitor are not competing for the same site so they will not affect each other
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In non-competitive inhibition, can the substrate prevent the binding of an inhibitor? Even at high substrate concentrations?
No, No
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How does the graph of non-competitive inhibitors in high substrate concentration compare to the graph of no inhibitor?
The rate having a non-competitive inhibitor at high substrate concentrations is lower
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Give an example of a reaction with competitive inhibitors
Succinate dehydrogenase is inhibited by malonate
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Give an example of a reaction with non-competitive inhibitors
Nitric oxide synthase is inhibited by morphine - Arginine --->
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Is competitive inhibition reversible?
Yes
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Is non-competitive inhibition reversible?
Yes
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When can maximum rate be acheived in a reaction with a competitive inhibitor?
When the concentration of substrate begins to exceed the amount of inhibitor
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Does maximum rate just immediately occur?
No - it takes a higher concentration of substrate to acheive maximum rate
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Do all enzymes have inhibitors that can bind to them?
No
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What is the name of the site that non-competitive inhibitors bind to on enzymes?
Allosteric site
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Other cards in this set

Card 2

Front

What do enzyme inhibitors do?

Back

Reduce the activity of an enzyme or prevent it completely

Card 3

Front

Name two main types of inhibitor

Back

Preview of the front of card 3

Card 4

Front

How does competitive inhibition work?

Back

Preview of the front of card 4

Card 5

Front

How long before the enzyme will resume work with competitive inhibition?

Back

Preview of the front of card 5
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