I have a soluble receptor and I am trying to develop the binding assay conditions using radiolebeled ligand. My problem is separating the bound from free radioligand. I've tried the precipitation method and it sort of works but I think I am loosing a lot of signal due to ligand dissociation during the precipitation time. I've also tried using dextran-coated charcoal but that is extremely not reproducible, in addition the charcoal doesn't completely remove the free radialigand and that severly effects the results.
Doe anyone know a better and quick method of separating free from bound radioligand for soluble receptors? Any references or advise would be appreciated,
Marek

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