1.9- ENZYME INHIBITION

Question 1

What are enzyme inhibitors?

Answer 1

substances that directly or indirectly interfere with functioning of active site of enzyme

Question 2

What do enzyme inhibitors do?

Answer 2

reduce enzyme activity

Question 3

What are two types of enzyme inhibitors?

Answer 3

competitive inhibitors

non-competitive inhibitors

Question 4

What do competitive inhibitors do?

Answer 4

bind to active site of enzyme

Question 5

What do non-competitive inhibitors do?

Answer 5

bind to enzyme at position other than active site

Question 6

What shape do competitive inhibitors have?

Answer 6

molecular shape similar to that of the substrate

Question 7

What does competitive inhibitors having a similar shape to the substrate allow them to do?

Answer 7

allow them to occupy the active site of an enzyme

Question 8

Why do competitive inhibitors compete with the substrate?

Answer 8

as they can occupy the active site so compete for with substrate for available active sites

Question 9

What determines the effect of the inhibitors on the enzyme activity?

Answer 9

difference between concentration of inhibitor and concentration of substrate

Question 10

What happens when if the substrate concentration is increased?

Answer 10

effect of the inhibitor is reduced

Question 11

Is the competitive inhibitor permanently bound to the active site?

Answer 11

no

Question 12

What happens when the competitive inhibitor leaves?

Answer 12

another molecule can take its place

Question 13

What could be the molecule that takes the place of the competitive inhibitor once it leaves?

Answer 13

a substrate or inhibitor molecule, depending on how much of each type is present

Question 14

sooner or later what will happen?

Answer 14

all the substrate molecules will occupy an active site

Question 15

What will make it longer for all the substrate molecules to occupy an active site?

Answer 15

greater the concentration of inhibitor

Question 16

What enzyme and substrate does an example of a competitive inhibitor occur with?

Answer 16

a respiratory enzyme that acts on succinate

Question 17

What is another compound that can inhibit the respiratory enzyme?

Answer 17

malonate

Question 18

How can malonate inhibit the respiratory enzyme?

Answer 18

has a very similar molecular shape to succinate

Question 19

As the malonate has a very similar molecular shape to the succinate what is it able to do?

Answer 19

easily combines with the enzyme and blocks succinate from combining with the enzyme’s active site

Question 20

What is another example of an inhibitor and of what enzyme?

Answer 20

inhibition of enzyme transpeptidase by penicillin

Question 21

What do non-competitive inhibtors do?

Answer 21

attach themselves to the enzyme at binding site which is not the active site

Question 22

Upon attaching to the enzyme, what does the non-competitive do?

Answer 22

alters shape of enzyme

Question 23

What happens as the shape of the enzyme is altered due to the non-competitive inhibitor?

Answer 23

active site of shape changes

Question 24

What happens as the shape of the active site is changed?

Answer 24

substrate molecule can no longer occupy active site so enzyme cannot function

Question 25

Why does increasing the substrate concentration not decrease the effect of the inhibitor ?

Answer 25

substrate and inhibitor not competing for same site