Receptor-Ligand Binding

Question 1

Define Binding Specificity

Answer 1

A ligand preferentially binds to one site over another.

Question 2

Define Ligand Specificity

Answer 2

A binding site usually has high specificity for particular ligands.

Question 3

Describe how drug side effects occur with respect to drug specificity vs selectivity.

Answer 3

Selectivity = ability of a given drug concentration to produce one effect over another (eg: therapeutic effect over side effect)

Side Effects

• Some drugs have side effects at therapeutic doses by action at the same target in other tissues or regions.
• Drugs binding to other targets at therapeutic doses can lead to side effects.
• As drug dose increases, the opportunity for the drug to bind to more targets with lower affinity increases => leads to side effects.

Question 4

Describe the main types of drug-target bonding.

Answer 4

Ionic bonding

Hydrogen bonding

Dipoles

Question 5

What are the 4 major drug targets?

Answer 5

Receptors
Ion Channels
Enzymes
Transporters

Question 6

Define Receptor Occupancy in relation to drug effect.

Answer 6

In the classic theory of receptor occupancy, drug effect is proportional to the number of receptors occupied by drug. Maximal effect occurs when all receptors are occupied.