Methods for purifying FXa variant proteins
Compositions are provided comprising recombinant variants of the human clotting Factor Xa. Such compositions include a wide variety of isoforms and post-translational modifications of FXa and are useful for treating subjects in need of hemostasis.
1. A method for purifying a Factor Xa (FXa) variant protein comprising the steps of:
(i) contacting a mixed mode chromatography (MMC) medium with a filtered cell culture medium containing a FXa variant protein,
(ii) eluting the FXa variant protein bound to the MMC chromatography medium,
(iii) contacting an anion exchange chromatography medium with the FXa variant protein eluted at step (ii),
(iv) eluting the FXa variant protein bound to the anion exchange chromatography medium,
(v) contacting a cation exchange chromatography medium with the FXa variant protein eluted at step (iv); and
(vi) eluting the FXa variant protein bound to the cation exchange chromatography medium,
wherein said FXa variant protein comprises a light chain and a heavy chain; and
wherein said FXa variant protein further comprises:
a substitution at the amino acid corresponding to position 146 in SEQ ID NO:1 with an amino acid selected from the group consisting of Leu, Phe, Asp and Gly;
a substitution at the amino acid corresponding to position 147 in SEQ ID NO:1 with an amino acid selected from the group consisting of Leu, Ala and Gly; or
a substitution at the amino acid corresponding to position 329 in SEQ ID NO:1 with an amino acid selected from the group consisting of Asn and Gly.
2. The method of claim 1 , wherein the mixed mode chromatography medium interacts with proteins via electrostatic interaction, hydrophobic interaction, hydrogen bonding, and thiophilic interaction.
3. The method of claim 1 , further comprising at least an additional step for inactivating or removing viruses.
4. The method of claim 3 , further comprising steps of ultrafiltration and diafiltration to concentrate the purified FXa variant protein.
5. The method of claim 1 , wherein the Factor Xa variant protein is a human Factor Xa variant protein.
6. The method of claim 1 , wherein the Factor Xa variant protein comprises a substitution at the amino acid corresponding to position 146 in SEQ ID NO:1 with Leu.
7. The method of claim 1 , wherein CHinese Hamster Ovary (CHO) cells were cultured in the cell culture medium.
8. The method of claim 1 , wherein the light chain comprises amino acids 1-139, 1-140, 1-141, or 1-142 from SEQ ID NO:1.
9. The method of claim 8 , wherein the light chain comprises a β-hydroxylated Asp, an O-linked hexose, and 9, 10, or 11 Gla residues.
10. The method of claim 1 , wherein the heavy chain is in a beta form.
11. The method of claim 10 , wherein the heavy chain is 239 or 241 amino acids in length and has a lysine as its carboxy terminal amino acid.
12. The method of claim 1 , wherein the heavy chain is in an alpha form.
13. The method of claim 12 , wherein the heavy chain is 253 amino acids in length and has a leucine as its carboxy terminal amino acid, or is 254 amino acids in length and has a lysine as its carboxy terminal amino acid.
14. The method of claim 12 , wherein the heavy chain comprises one or two O-linked glycans.
15. The method of claim 14 , wherein one or both O-linked glycans is mono-sialylated or di-sialylated.