Recognition Forces in Molecular Pharmacology and Biology

The left-hand side of Fig. 1 lists all major recognition forces of significance in molecular pharmacology and biology. Most of them are classified as electrostatic, although some are more electrodynamic than electrostatic, i.e., charge transfer interactions, ion-induced dipole interactions, induction forces, and dispersion forces.

This classification is an extrathermodynamic one since it voluntarily ignores the division between the enthalpic and entropic components of the binding free energy. Such a neglect is tolerable in the present context, for two reasons. First, many if not all of the forces listed in Fig. 1 contain both components, and their interpretation in terms of enthalpy and entropy is a different issue altogether. And second, lipophilicity is also an extrathermodynamic parameter which can be interpreted as such.

Recognition Forces

Electrostatic interactions

Ionic bonds

Aryl-aryl charge transfer interactions

Lipophilicity

Ion - dipole (permanent, induced) bonds Reinforced H-bonds Normal H-bonds

Polarity

Van der Waals forces

Orientation forces (permanent dipole - permanent dipole)

Induction forces (permanent dipole - Induced dipole)

Dispersion forces (instantaneous dipole - induced dipole)

Hydrophobicity

Hydrophobic interactions

Figure 1. A comparison between recognition forces in molecular pharmacology and biology (left panel) and intermolecular forces encoded in lipophilicity (right panel).

Figure 1. A comparison between recognition forces in molecular pharmacology and biology (left panel) and intermolecular forces encoded in lipophilicity (right panel).

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