Method of purifying pegylated proteins
The invention relates to a method of purifying PEGylated proteins by removing impurities from samples containing PEGylated proteins, in particular, but not exclusively vitamin K-dependent blood coagulation factors such as Factor IX (FIX), to proteins purified by said method and to the use of said purified proteins in therapy, in particular but not exclusively, for the treatment of diseases alleviated by blood coagulation factors such as the prophylactic treatment of hemophilia.
1. A method for purifying a PEGylated protein which comprises performing anion exchange chromatography with an elution buffer, characterized in that said chromatography comprises an impurity removal step prior to elution wherein said impurity removal step comprises washing said anion exchange column with an acidic buffer at a pH of between 3.9 and 4.5, wherein the PEGylated protein is selected from the group consisting of Factor II (FII), Factor VII (FVII), Factor IX (FIX), Factor X (FX), protein S and protein C.
2. The method of claim 1 , wherein said impurity is ST3 beta-galactoside alpha-2,3-sialyltransferase 3 (ST3Gal3).
3. The method of claim 1 , wherein the impurity removal step comprises washing with an acidic buffer at a pH of selected from the group consisting of between 4.0 and 4.5 and between 4.0 and 4.4.
4. The method of claim 1 , wherein the acidic buffer comprises sodium acetate or acetic acid, wherein the concentration of sodium acetate is about 50 mM, and wherein the concentration of acetic acid is about 140 mM.
5. The method of claim 1 , wherein an equilibration step is performed prior to the acidic wash step.
6. The method of claim 5 , wherein the equilibration step comprises application of an equilibration buffer at a pH of between 5 and 7.
7. The method of claim 5 , wherein the equilibration buffer comprises sodium acetate and acetic acid, wherein the concentration of acetic acid is about 10 mM, and wherein the concentration of sodium acetate is about 90 mM sodium.
8. The method of claim 1 , wherein the PEGylated protein is selected from the group consisting of Factor IX (FIX) and Factor VII (FVII).
9. The method of claim 1 , wherein the anion exchange material comprises HQ.
10. The method of claim 9 , wherein the HQ anion exchange material comprises Poros® HQ.
11. The method of claim 9 , wherein the HQ anion exchange material comprises Poros® 50 HQ.