Buffer system for protein purification

1. A chromatography system consisting essentially of:

i. a sodium chloride-free multi-component buffer system for the purification of a recombinant protein, and

ii. a series of chromatography steps,

wherein the chromatography steps comprise affinity chromatography and one or more additional chromatography steps chosen from: anion exchange chromatography, cation exchange chromatography, and mixed-mode chromatography,

wherein the chromatography steps are operated in a mode chosen from: bind-elute mode and flow-through mode,

wherein the sodium chloride-free multi-component buffer system consists essentially of: (a) an organic acid, (b) an organic base, and (c) at least one component chosen from an alkaline metal and an ammonium salt of the conjugate base of the organic acid of (a); and

wherein the sodium chloride-free multi-component buffer system is used throughout the series of chromatography steps.

2. The system of claim 1 , wherein the affinity chromatography is performed using a superantigen immobilized on a solid phase.

3. The system of claim 2 , wherein the superantigen is chosen from: Protein A, Protein G, and Protein L.

4. The system of claim 1 , wherein the organic acid is chosen from: formic acid, acetic acid, citric acid, malic acid, maleic acid, glycine, glycylclycine, succinic acid, TES (2-{[tris(hydroxymethyl)methyl]amino}ethanesulfonic acid), MOPS (3-(N -morpholino)propanesulfonic acid), PIPES (piperazine-N,N′-bis(2-ethanesulfonic acid)), and MES (2-(N-morpholino)ethanesulfonic acid).

5. The system of claim 1 , wherein the organic base is chosen from: tris base, Bis-Tris, Bis-Tris-Propane, Bicine (N,N-bis(2-hydroxyethyl)glycine), HEPES (4-2-hydroxyethyl-1-piperazineethanesulfonic acid), TAPS (3-{[tris(hydroxymethyl)methyl]amino}propanesulfonic acid), and Tricine (N-tris(hydroxymethyl)methylglycine).

6. The system of claim 1 , wherein the alkaline metal or ammonium salt of the conjugate base of the organic acid is the sodium, potassium, or ammonium salt of the conjugate base of the organic acid.

7. The system of claim 1 , wherein the organic acid is acetic acid.

8. The system of claim 1 , wherein the organic base is tris base.

9. The system of claim 1 , wherein the organic acid is acetic Acid, and the conjugate base of acetic acid is the sodium salt.

10. The system of claim 1 , wherein the recombinant protein is an antigen binding protein.

11. The system of claim 10 , wherein the antigen binding protein is an antibody of the IgG class.

12. The system of claim 10 wherein the antigen binding protein is a immunoglobulin single variable domain.

13. The system of claim 1 , wherein the series of chromatographic steps comprises protein A chromatography and flowthrough anion exchange chromatography.

14. The system of claim 1 , wherein the series of chromatographic steps comprises protein A chromatography, flowthrough anion exchange chromatography, and cation exchange chromatography.

15. The system of claim 1 , wherein the series of chromatographic steps comprises protein A chromatography performed in the presence of 55 mM tris base, 45 mM acetic acid, at about pH7.5.

16. The system of claim 1 wherein the sequence of chromatographic steps comprises flowthrough anion exchange chromatography performed in the presence of 55 mM tris base, 45 mM acetic acid, at about pH 7.5.

17. The system of claim 1 wherein the sequence of chromatographic steps comprises cation exchange chromatography performed in the presence of 25 mM sodium acetate, 12.1 mM acetic acid, at about pH 5.0.

18. The system of claim 1 , wherein the series of chromatographic steps comprises protein A chromatography, and flow through anion exchange chromatography performed in the presence of 55 mM tris base, 45 mM acetic acid, at about pH 7.5.

19. The system of claim 1 , wherein the series of chromatographic steps comprises protein A chromatography, and cation exchange chromatography performed in the presence of 25 mM sodium acetate, 12.1 mM acetic acid, at about pH 5.0.