Inhibition Of Enzymes

Question 1

Why s enzyme inhibition important

Answer 1

Enzyme inhibition is important for clinical drug therapy e.g metothrexate in cancer chemotherapy to semi selectively inhibit DNA synthesis of malignant cells

Question 2

Irreversible inhibitor

Answer 2

Inhibitors binds to enzyme and this can be covalent or non covalent
This is very slow disassociation and permanently blocks the action of an enzyme

Question 3

Reversible inhibitor

Answer 3

Inhibitor prevents substrate binding
The inhibitor binds to enzyme and there is rapid disassociation
Inactivates an enzyme through non covalent reversible interactions

Question 4

Competitive inhibition

Answer 4

Inhibitor competes with substrate for active site forming an ES complex
The rate of catalysis is lowered by reducing formation of the ES complex

Question 5

Non competitive inhibition

Answer 5

Binds to the enzyme at a site other than the active site. Inhibitor and substrate can simultaneously be attached to the enzyme
The substrate and inhibitor have no effect on the binding of the other
Additional of substrate cannot overcome inhibition

Question 6

Mixed inhibition

Answer 6

Mixed type inhibition is similar to non-competitive
inhibition. However, the binding of the substrate or the inhibitor affect the affinity of each other for the enzyme
This means that the binding of the substrate to the
enzyme is reduced in the presence of the inhibitor

Question 7

Uncompetitive inhibition

Answer 7

Very rare class: An uncompetitive inhibitor binds only to the enzyme substrate complex and enhances the binding of substrate (reducing KM)
The resultant enzyme, inhibitor, substrate complex has a reduced activity and only forms the product slowly so that v max is reduced