1.9: Enzyme inhibition

Question 1

Enzyme inhibitors

Answer 1

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

Question 2

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

Answer 2

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

Question 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?

Answer 3

There are a number of types of enzyme inhibitors, 2 of which are:

1. Competitive inhibitors
2. Non-competitive inhibitors

Question 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?

Answer 4

Competitive inhibitors bind to the active site of the enzyme

Question 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?

Answer 5

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

Question 6

Competitive inhibitors:

Competitive inhibitors have a molecular shape similar to what?

Answer 6

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

Question 7

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

Answer 7

This allows them to occupy the active site of an enzyme

Question 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?

Answer 8

They therefore compete with the substrate for the available active sites

Question 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?

Answer 9

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

Question 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?

Answer 10

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

Question 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?

Answer 11

The competitive inhibitor is not permanently bound to the active site

Question 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?

Answer 12

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

Question 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?

Answer 13

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

Question 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?

Answer 14

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

Question 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?

Answer 15

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

Question 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?

Answer 16

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

Question 17

Competitive inhibitors:

An example of competitive inhibition occurs with what?

Answer 17

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

Question 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?

Answer 18

Another compound, called malonate, can inhibit the enzyme

Question 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?

Answer 19

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

Question 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?

Answer 20

It therefore:

1. Easily combines with the enzyme
2. Blocks succinate from combining with the enzyme’s active site

Question 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?

Answer 21

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

Question 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?

Answer 22

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

Question 23

Non-competitive inhibitors:

Non-competitive inhibitors attach themselves to the enzyme where?

Answer 23

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

Question 24

Non-competitive inhibitors:

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

Answer 24

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

Question 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?

Answer 25

Upon attaching to the enzyme, the non-competitive inhibitor alters the shape of:

1. The enzyme
2. Thus its active site

Question 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?

Answer 26

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

Question 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?

Answer 27

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

Question 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?

Answer 28

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

Question 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?

Answer 29

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

Question 30

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

Answer 30

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

Question 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?

Answer 31

The reaction takes place as normal

Question 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?

Answer 32

The inhibitor prevents the normal enzyme-substrate complex being formed

Question 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?

Answer 33

The reaction rate is reduced