\[K_A=\frac{1}{K_D}\]
Variables
Ka[KA]association affinity constant
Kd[KD]equilibrium dissociation constant
Description
What is this formula?
The Receptor Affinity Constant Relation expresses the inverse relationship between the association affinity constant (Ka) and the equilibrium dissociation constant (Kd).
A lower Kd indicates higher ligand affinity, while a higher Ka indicates stronger association between ligand and receptor.
When to use it
Use this formula when converting between Kd and Ka in receptor pharmacology, ligand binding studies, biochemistry, or molecular pharmacology.
Example
Given:
Kd = 2 nM
Formula:
Ka = 1/Kd
Substitution:
Ka = 1/2
Ka = 0.5 nM⁻¹
Result:
The association affinity constant is 0.5 nM⁻¹.
Applications
- Receptor pharmacology
- Ligand affinity comparison
- Binding assay interpretation
- Molecular pharmacology
- Biochemistry
- Drug discovery