Question

Sketch a binding curve (% bound ligand versus ligand concentration) for cooperative and noncooperative binding.

Short answer

The cooperative binding shows a sigmoidal curve, while the non-cooperative binding shows a logarithmic curve.

Step-by-step solution

Cooperative binding

For cooperative binding, binding the ligand to one subunit of the binding protein increases the ligand-affinity for the other subunits of the binding protein. Due to this increased affinity, an S-shaped or sigmoidal curve is observed. For example, the binding of oxygen to hemoglobin is cooperative.

Non-cooperative binding 

For noncooperative binding, binding one ligand to one subunit of the binding protein does not affect the ligand-affinity for the other subunits of the binding proteins. In this case, a logarithmic curve is observed. For example, the binding of oxygen to myoglobin is noncooperative.

The binding curve