Hello Alka,

I'm not really familiar with MST, but if what you're following is the binding of a protein (ligand) to another protein and you had this phenomenon at high concentration only... It might be that the "free or available/effective" fraction of your ligand changes at high concentration due to different possibilities. For example, a) the ligand can form now aggregates or prefers to interact with itself forming oligomers (?) or b) difference in solubility, in particular if the ligand is somewhat hydrophobic. I have seen this behavior in, for instance, enzyme kinetics where one substrate is hydrophobic... you do have a range of concentration where the ligand behaves ideally, but at high concentrations the substrate forms micelles, thus decreasing its "effective" concentration. Hope these ideas help you.

Best,

Alfredo

Alfredo Cabrera-Orefice Thankyou for your answer.

My personal experience with MST is as follows. When you do MST for protein-protein interaction, you will not get saturation point as you get while studying protein-ligand interaction using MST. The reason could be when temperature rises, one of the two proteins starts losing structure and thus the signal starts to drop which gives very small range of saturation points unlike in case of protein-ligand MST. In case of protein-ligand MST you get nice 4-5 point range of saturation points.

I am also having same issues as you. Trying several concentrations of both protein-protein and protein-ligand but cannot get that full saturation.

What is the ideal concentration that may give this saturation?