1. Parameters to be calculated
Kd – the dissociation constant
The lower the value of Kd the higher the binding affinity
Has molar units
Values usually in nM range (10-9M)
Bmax – number of receptors
Often quoted /mg of protein
Can be very low fmole/mg (10-15 mole/mg)

2. Radioligand binding experiments
Two types
Saturation binding
Competition
Saturation Binding
Can calculate BOTH Kd and Bmax
Disadvantage – rather expensive – use a lot of radioligand
Only calculate Kd
Cheaper – use less radioligand

3. Saturation binding expt
Preparation of protein
Mix with radioligand
Incubate
Filter
Count radioactivity