The present invention provides a process for dissociating Fc-containing molecules from complexes of Protein A/Fc-containing molecules or mixtures containing Fc-containing molecules and Protein A. The association, e.g., by hydrophobic interactions, between the Fc-containing molecules and Protein A can be reduced or inhibited by raising the pH of dissociation. The pH of dissociation can be raised by addition of agents capable of inhibiting hydrophobic interactions, including buffers containing arginine and/or ethylene glycol, to the mixture, either prior to adding the mixture to the column chromatography substrate, after adding the mixture to the column chromatography substrate, or both prior to and after adding the mixture to the column chromatography substrate. Separation of Fc-containing molecules from Protein A can be performed on a number of different column chromatographic substrates, including column chromatographic substrates contained in Q columns (Q column chromatography substrate), HIC columns (hydrophobic interaction column chromatography substrate), and IMAC columns (metal chelate column chromatography substrate).

The present invention provides a process for isolating and purifying highly anionic target proteins, for example, sulfated proteins. Sulfated proteins have five (5) or more, sulfations. In a preferred embodiment, the sulfated protein has six (6) sulfations, e.g., six sulfations on N-terminal tyrosine residues, as embodied in PSGL-1 (P-selectin glycoprotein ligand).