For protein purification, we typically use affinity column purification. Unless the gene of interest is pre-cloned, and ligands for the affinity column can be purchased or provided, we generally use His-tag Nickel and GST to purify the expressed proteins. For higher levels of purity, we can further subject the eluted fractions through Size-exclusion chromatography to obtain purer fractions of the eluate. We can provide purity >90% with this.
         
For work that requires obtaining only pure biologically active proteins, we recommend the use of affinity column purification through known ligands. We can purify the compounds with the columns if the known ligands are provided to us or commercially available. If you are providing us the ligand, we require at least 2-3 mgs of the ligand to purify 7-10 mgs of the desired protein depending on the stability of the ligand and the nature of the protein-ligand interaction. For very stable ligands that can be easily dissociated from the prtoein, we can naturally purify larger amounts.