Question

(BASED ON THE BOOK "The Organic Chemistry of Drug Design and Drug Action" Richard B. Silverman 3rd Addition)

Questions will be answered according to the CHAPTER 3 of the book:

1. What are the two key properties of receptor function.
2. Why is a drug with a lower K_d more potent than one with a higher K_d?
3. Give an example of an ion-dipole interaction (use real structures).
4. Why is intramolecular hydrogen bonding so important in drug design?

Answer 1

1a. Receptors are highly specific to their ligands.

b. These are present either on the cell surface or inside the cell in the cytoplasm or in the nucleus.

2. The strength of the binding (interaction) of a ligand and its receptor can be described by affinity. The higher the Kd value, the weaker the binding and the lower the affinity. The opposite occurs when a drug has a low Kd. Thus a drug with a lower K_d is more potent than one with a higher K_d because the drug with lower Kd binds its receptor strongly than the other drug which has higher Kd.

3. An example of the ion-dipole interaction is the interaction between a Na⁺ ion and water (H₂O) where the sodium ion and oxygen atom are attracted to each other, while the sodium and hydrogen are repelled by each other.

4.  Intramolecular hydrogen bonds are those which occur within one single molecule. This occurs when two functional groups of a molecule can form hydrogen bonds with each other. It is used to modulate biological and chemical properties of interest.