A pharmaceutical company is developing a drug that targets a specific protein receptor. They want to ensure the drug binds reversibly and non-covalently to the receptor. Which type of bonding is LEAST likely to be involved in the reversible binding of this drug to its receptor?
- ACovalent bonding
- BHydrogen bonding
- CIonic interactions
- DVan der Waals forces
Show answer & explanationAnswer & explanation
Correct answer: A. Covalent bonding
Reversible binding in biological systems, such as drug-receptor interactions, primarily involves non-covalent forces. These include hydrogen bonding, ionic interactions (salt bridges), and Van der Waals forces (London dispersion forces, dipole-dipole). Covalent bonding, by definition, involves the sharing of electrons and is typically much stronger and less readily reversible under physiological conditions. While some drugs form irreversible covalent bonds, the question specifies 'reversible binding'.
Why the other options are wrong
- B. Hydrogen bonding is a common and important non-covalent interaction in reversible drug-receptor binding.
- C. Ionic interactions (salt bridges) are strong non-covalent forces often involved in reversible drug-receptor binding.
- D. Van der Waals forces (including London dispersion and dipole-dipole) are weak but ubiquitous non-covalent interactions that contribute to reversible binding.
Reversible Drug-Receptor Binding
Reversible drug-receptor binding involves non-covalent interactions where the drug can associate and dissociate from its target, allowing for dynamic biological responses and eventual clearance.
- Primarily involves non-covalent forces.
- Examples: H-bonding, ionic, Van der Waals.
- Allows for drug dissociation and termination of effect.
- Covalent binding is generally irreversible.
Memory trick: H-IV: Hydrogen, Ionic, Van der Waals.