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Flashcards in 1.9: Enzyme inhibition Deck (33):
1

Enzyme inhibitors

Enzyme inhibitors are substances that:
1. Directly
Or,
2. Indirectly
interfere with the functioning of the active site of an enzyme

2

Enzyme inhibitors are substances that directly or indirectly interfere with the functioning of the active site of an enzyme and so do what?

Enzyme inhibitors are substances that directly or indirectly:
1. Interfere with the functioning of the active site of an enzyme
2. So reduce its activity

3

Enzyme inhibitors are substances that directly or indirectly interfere with the functioning of the active site of an enzyme and so reduce its activity.
There are a number of types of enzyme inhibitors, 2 of which are what?

There are a number of types of enzyme inhibitors, 2 of which are:
1. Competitive inhibitors
2. Non-competitive inhibitors

4

Enzyme inhibitors are substances that directly or indirectly interfere with the functioning of the active site of an enzyme and so reduce its activity.
There are a number of types of enzyme inhibitors, 2 of which are competitive inhibitors and non-competitive inhibitors.
What do competitive inhibitors do?

Competitive inhibitors bind to the active site of the enzyme

5

Enzyme inhibitors are substances that directly or indirectly interfere with the functioning of the active site of an enzyme and so reduce its activity.
There are a number of types of enzyme inhibitors, 2 of which are competitive inhibitors and non-competitive inhibitors.
What do non-competitive inhibitors do?

Non-competitive inhibitors bind to the enzyme at a position other than the active site

6

Competitive inhibitors:
Competitive inhibitors have a molecular shape similar to what?

Competitive inhibitors have a molecular shape similar to that of the substrate

7

Competitive inhibitors:
Competitive inhibitors have a molecular shape similar to that of the substrate.
This allows them to do what?

This allows them to occupy the active site of an enzyme

8

Competitive inhibitors:
Competitive inhibitors have a molecular shape similar to that of the substrate.
This allows them to occupy the active site of an enzyme.
They therefore do what?

They therefore compete with the substrate for the available active sites

9

Competitive inhibitors:
Competitive inhibitors have a molecular shape similar to that of the substrate.
This allows them to occupy the active site of an enzyme.
They therefore compete with the substrate for the available active sites.
It is what that determines the effect that this has on enzyme activity?

It is the difference between the:
1. Concentration of the inhibitor
2. Concentration of the substrate
that determines the effect that this has on enzyme activity

10

Competitive inhibitors:
Competitive inhibitors have a molecular shape similar to that of the substrate.
This allows them to occupy the active site of an enzyme.
They therefore compete with the substrate for the available active sites.
It is the difference between the concentration of the inhibitor and the concentration of the substrate that determines the effect that this has on enzyme activity.
If the substrate concentration is increased, the effect of the inhibitor is what?

If the substrate concentration is increased, the effect of the inhibitor is reduced

11

Competitive inhibitors:
Competitive inhibitors have a molecular shape similar to that of the substrate.
This allows them to occupy the active site of an enzyme.
They therefore compete with the substrate for the available active sites.
It is the difference between the concentration of the inhibitor and the concentration of the substrate that determines the effect that this has on enzyme activity.
If the substrate concentration is increased, the effect of the inhibitor is reduced.
The competitive inhibitor is not what to the active site?

The competitive inhibitor is not permanently bound to the active site

12

Competitive inhibitors:
Competitive inhibitors have a molecular shape similar to that of the substrate.
This allows them to occupy the active site of an enzyme.
They therefore compete with the substrate for the available active sites.
It is the difference between the concentration of the inhibitor and the concentration of the substrate that determines the effect that this has on enzyme activity.
If the substrate concentration is increased, the effect of the inhibitor is reduced.
The competitive inhibitor is not permanently bound to the active site and so, when it leaves, what?

The competitive inhibitor is not permanently bound to the active site and so, when it leaves, another molecule can take its place

13

Competitive inhibitors:
Competitive inhibitors have a molecular shape similar to that of the substrate.
This allows them to occupy the active site of an enzyme.
They therefore compete with the substrate for the available active sites.
It is the difference between the concentration of the inhibitor and the concentration of the substrate that determines the effect that this has on enzyme activity.
If the substrate concentration is increased, the effect of the inhibitor is reduced.
The competitive inhibitor is not permanently bound to the active site and so, when it leaves, another molecule can take its place.
This could be what?

This could be:
1. A substrate
Or,
2. An inhibitor molecule

14

Competitive inhibitors:
Competitive inhibitors have a molecular shape similar to that of the substrate.
This allows them to occupy the active site of an enzyme.
They therefore compete with the substrate for the available active sites.
It is the difference between the concentration of the inhibitor and the concentration of the substrate that determines the effect that this has on enzyme activity.
If the substrate concentration is increased, the effect of the inhibitor is reduced.
The competitive inhibitor is not permanently bound to the active site and so, when it leaves, another molecule can take its place.
This could be a substrate or an inhibitor molecule, depending on what?

This could be:
1. A substrate
Or,
2. An inhibitor molecule
,depending on how much of each type is present

15

Competitive inhibitors:
Competitive inhibitors have a molecular shape similar to that of the substrate.
This allows them to occupy the active site of an enzyme.
They therefore compete with the substrate for the available active sites.
It is the difference between the concentration of the inhibitor and the concentration of the substrate that determines the effect that this has on enzyme activity.
If the substrate concentration is increased, the effect of the inhibitor is reduced.
The inhibitor is not permanently bound to the active site and so, when it leaves, another molecule can take its place.
This could be a substrate or an inhibitor molecule, depending on how much of each type is present.
Sooner or later, what will happen?

Sooner or later, all the substrate molecules will occupy an active site

16

Competitive inhibitors:
Competitive inhibitors have a molecular shape similar to that of the substrate.
This allows them to occupy the active site of an enzyme.
They therefore compete with the substrate for the available active sites.
It is the difference between the concentration of the inhibitor and the concentration of the substrate that determines the effect that this has on enzyme activity.
If the substrate concentration is increased, the effect of the inhibitor is reduced.
The inhibitor is not permanently bound to the active site and so, when it leaves, another molecule can take its place.
This could be a substrate or an inhibitor molecule, depending on how much of each type is present.
Sooner or later, all the substrate molecules will occupy an active site, but the greater the concentration of inhibitor, what?

Sooner or later, all the substrate molecules will occupy an active site, but the greater the concentration of inhibitor, the longer this will take

17

Competitive inhibitors:
An example of competitive inhibition occurs with what?

An example of competitive inhibition occurs with an important respiratory enzyme that acts on succinate

18

Competitive inhibitors:
An example of competitive inhibition occurs with an important respiratory enzyme that acts on succinate.
Another compound, called what, can do what?

Another compound, called malonate, can inhibit the enzyme

19

Competitive inhibitors:
An example of competitive inhibition occurs with an important respiratory enzyme that acts on succinate.
Another compound, called malonate, can inhibit the enzyme, because it has what?

Another compound, called malonate, can inhibit the enzyme, because it has a very similar molecular shape to succinate

20

Competitive inhibitors:
An example of competitive inhibition occurs with an important respiratory enzyme that acts on succinate.
Another compound, called malonate, can inhibit the enzyme, because it has a very similar molecular shape to succinate.
It therefore does what?

It therefore:
1. Easily combines with the enzyme
2. Blocks succinate from combining with the enzyme's active site

21

Competitive inhibitors:
An example of competitive inhibition occurs with an important respiratory enzyme that acts on succinate.
Another compound, called malonate, can inhibit the enzyme, because it has a very similar molecular shape to succinate.
It therefore easily combines with the enzyme and blocks succinate from combining with the enzyme's active site.
Another example of competitive inhibition is what?

Another example of competitive inhibition is the inhibition of the enzyme transpeptidase

22

Competitive inhibitors:
An example of competitive inhibition occurs with an important respiratory enzyme that acts on succinate.
Another compound, called malonate, can inhibit the enzyme, because it has a very similar molecular shape to succinate.
It therefore easily combines with the enzyme and blocks succinate from combining with the enzyme's active site.
Another example of competitive inhibition is the inhibition of the enzyme transpeptidase by what?

Another example of competitive inhibition is the inhibition of the enzyme transpeptidase by penicillin

23

Non-competitive inhibitors:
Non-competitive inhibitors attach themselves to the enzyme where?

Non-competitive inhibitors attach themselves to the enzyme at a binding site

24

Non-competitive inhibitors:
Non-competitive inhibitors attach themselves to the enzyme at a binding site that is not what?

Non-competitive inhibitors attach themselves to the enzyme at a binding site that is not the active site

25

Non-competitive inhibitors:
Non-competitive inhibitors attach themselves to the enzyme at a binding site that is not the active site.
Upon attaching to the enzyme, the non-competitive inhibitor does what?

Upon attaching to the enzyme, the non-competitive inhibitor alters the shape of:
1. The enzyme
2. Thus its active site

26

Non-competitive inhibitors:
Non-competitive inhibitors attach themselves to the enzyme at a binding site that is not the active site.
Upon attaching to the enzyme, the non-competitive inhibitor alters the shape of the enzyme and thus its active site in such a way that what?

Upon attaching to the enzyme, the non-competitive inhibitor alters the shape of:
1. The enzyme
2. Thus its active site
in such a way that substrate molecules can no longer occupy it

27

Non-competitive inhibitors:
Non-competitive inhibitors attach themselves to the enzyme at a binding site that is not the active site.
Upon attaching to the enzyme, the non-competitive inhibitor alters the shape of the enzyme and thus its active site in such a way that substrate molecules can no longer occupy it and so the enzyme cannot do what?

Upon attaching to the enzyme, the non-competitive inhibitor alters the shape of the enzyme and thus its active site in such a way that:
1. Substrate molecules can no longer occupy it
2. So the enzyme cannot function

28

Non-competitive inhibitors:
Non-competitive inhibitors attach themselves to the enzyme at a binding site that is not the active site.
Upon attaching to the enzyme, the non-competitive inhibitor alters the shape of the enzyme and thus its active site in such a way that substrate molecules can no longer occupy it and so the enzyme cannot function.
As the substrate and the inhibitor are not what?

As the:
1. Substrate
2. Inhibitor
are not competing for the same site

29

Non-competitive inhibitors:
Non-competitive inhibitors attach themselves to the enzyme at a binding site that is not the active site.
Upon attaching to the enzyme, the non-competitive inhibitor alters the shape of the enzyme and thus its active site in such a way that substrate molecules can no longer occupy it and so the enzyme cannot function.
As the substrate and the inhibitor are not competing for the same site, an increase in substrate concentration does not do what?

As the:
1. Substrate
2. Inhibitor
are not competing for the same site, an increase in substrate concentration does not decrease the effect of the inhibitor

30

Non-competitive inhibitors:
1. The inhibitor is absent.
The substrate does what?

The substrate attaches to the active site of the enzyme in the normal way

31

Non-competitive inhibitors:
1. The inhibitor is absent.
The substrate attaches to the active site of the enzyme in the normal way.
The reaction takes place how?

The reaction takes place as normal

32

Non-competitive inhibitors:
1. The inhibitor is absent.
The substrate attaches to the active site of the enzyme in the normal way.
The reaction takes place as normal.
2. The inhibitor is present.
The inhibitor prevents what being formed?

The inhibitor prevents the normal enzyme-substrate complex being formed

33

Non-competitive inhibitors:
1. The inhibitor is absent.
The substrate attaches to the active site of the enzyme in the normal way.
The reaction takes place as normal.
2. The inhibitor is present.
The inhibitor prevents the normal enzyme-substrate complex being formed.
The reaction rate is what?

The reaction rate is reduced