I am working to crystallize a protein-ligand complex. I did a preliminary melting curve analysis for the protein in the absence and presence of 2 ligands (dissolved in protein buffer). I kept the other controls as buffer an a known standard to confirm instrument performance. All expts done in triplicates.

Now the results are like : Tm of protein alone is 56 deg, Tm in the presence of Lig1 conc. of 0.05mM, 0.1mM, 1.0mM and 10.0mM is 56.2, 56.1, 56.0 and 53.5 respectively !! Tm in the presence of Lig 2 conc. of 0.05mM, 0.1mM, 1.0mM, 4.0mM and 10.0mM is 56.2, 56.1, 54.9, 52.3 and 50.6 respectively !!  

Although the effective delta Tm for both is different at higher concentration, but both are kind of making protein less stable. So i was wondering, will it be difficult to co-crystallize them !! Any suggestions in this regard are highly appreciated !!

Thanks

Monica