Measuring Protein-Ligand Binding Strength

Protein-ligand binding strength can be measured with the equilibrium binding constant, Kb. This value describes how strongly a protein binds a ligand when the reaction has reached equilibrium. In a bound complex, the protein and ligand are joined as PL, while P and L are the unbound forms.

Kb can...

In the cell, proteins randomly collide with other molecules, such as other proteins, nucleic acids, and small-molecule ligands.

If the binding is non-specific, few non-covalent interactions between the molecules result in a brief association.

If a specific ligand binds to the protein, it forms extensive non-covalent interactions al...