Purification method for divalent cation binding proteins on anion exchange resin

1. A method for the purification of a Factor IX (FIX) protein comprising the steps of:

(a) loading an anion exchange resin material with the Factor IX (FIX) protein in a loading buffer, wherein the loading buffer contains a chelating agent and no free divalent cations;

(b) washing the loaded anion exchange resin material prepared in step (a) with a wash buffer, wherein the wash buffer does not contain sufficient divalent cations to elute the Factor IX (FIX) protein,

wherein the salt concentration of the wash buffer is between 165 mM and 175 mM,

wherein the pH of the wash buffer is less than 6.5;

(c) washing the loaded anion exchange resin material prepared in step (b) with a wash buffer, wherein the wash buffer does not contain sufficient divalent cations to elute the Factor IX (FIX) protein and wherein the pH of the wash buffer is about 7.3 to 7.5, and

wherein there is no additional wash step after (b) and before (c); and

(d) eluting the Factor IX (FIX) protein with an elution buffer comprising at least one divalent cation to form an eluate containing the Factor IX (FIX) protein;

wherein the elution buffer has a pH at least 0.5 pH units higher than the pH of the loading buffer in step (a),

wherein the elution buffer has a pH at least 1.5 pH units higher than the pH of the wash buffer in step (b),

wherein the pH of the elution buffer is greater than or equal to 7.9,

and wherein the FIX protein in the eluate has a purity with respect to host cell protein impurities of at least 98% w/w.

2. The method of claim 1 , wherein the elution buffer in step (d) has a pH at least 2.0 pH units higher than the pH of the wash buffer in step (b).

3. The method according to claim 1 , wherein the wash buffer of step (b) has a conductivity that is equal or lower than the conductivity of the elution buffer in step (d).

4. The method according to claim 1 , wherein the at least one divalent cation in step (d) is selected from the group consisting of Ca 2+ , Be 2+ , Ba 2+ , Mg 2+ , Mn 2+ , Sr 2+ , Zn 2+ , Co 2+ , Ni 2+ , and Cu 2+ , and a combination thereof.

5. The method according to claim 1 , wherein the anion exchange resin material has a positively charged group which is selected from the group, consisting of diethylaminoethane (DEAE), dimethylaminoethane (DMAE), trimethylaminoethyl (TMAE), polyethyleneimine (PEI), quaternary aminoalkyl, quaternary aminoethane (QAE), and quaternary ammonium (Q).

6. The method according to claim 1 , wherein the anion exchange resin material carries a primary amine as ligand which is selected from the group, consisting of aminohexyl, benzamidine, lysine, and arginine.

7. The method of claim 1 , wherein the wash buffer in step (b) and the wash buffer in step (c) do not contain divalent cations.

8. The method of claim 1 , wherein the FIX protein in the eluate has a purity with respect to host cell protein impurities of at least 99% w/w.