Question

Estimate K from the following data describing ligand binding to a protein.

Short answer

The estimated value of K is 0.6 mM.

Step-by-step solution

Definition of K

The value of K could be conveniently defined as the value of p₅₀, which is the ligand concentration at which the protein is 50% saturated, that is, half saturated.

If we could plot Y value versus [Ligand], then we would be able to determine the ligand concentration at which the protein is fully saturated, as well as, is 50% saturated.

Plot of Y versus [Ligand]

At the saturation point, Y = 1. Thus, at half saturation, Y = 0.5.

For Y= 0.5, the corresponding ligand concentration ([Ligand]) is 0.6 mM. Thus, the estimated value of K (or p₅₀) is 0.6 mM.