Affinity chromatography matrix

1. A method of separating one or more immunoglobulin containing proteins from a liquid, which method comprises:

(a) contacting the liquid with a separation matrix comprising ligands immobilised to a support;

(b) allowing said immunoglobulin containing proteins to adsorb to the matrix by interaction with the ligands;

(c) an optional step of washing the immunoglobulin containing protein adsorbed matrix;

(d) recovering said immunoglobulin containing proteins by contacting the matrix with an eluent which releases the proteins;

the improvement being that each of said ligands comprises one or more monomeric domains of staphylococcal Protein A (SpA) (E, D, A, B, C) or Protein Z,

wherein in at least one of the one or more monomers, the Asparagine or Histidine at the position corresponding to H18 of the B domain of Protein A or Protein Z has been substituted with a Serine, and

wherein the ligand provides an increase in elution pH compared to non-substituted ligand with essentially unaltered or improved dynamic binding capacity and yield.

2. The method of claim 1 , wherein said one or more domains of Protein A or Protein Z are two or more copies from the same domain of SpA (E, D, A, B, C) or Protein Z.

3. The method of claim 1 , wherein said one or more domains of Protein A or Protein Z are two or more domains selected from a domain of SpA (E, D, A, B, C) or Protein Z.

4. The method of claim 1 , wherein said one or more domains of Protein A or Protein Z are selected from domain B, domain C or Protein Z.

5. The method of claim 1 , wherein the ligands are multimers of monomeric domains and in at least one of the monomeric domains in the multimer the Asparagine or Histidine at the position corresponding to H18 of B domain of Protein A or Protein Z has been substituted with a Serine.

6. The method of claim 5 , wherein the Asparagine or Histidine at the position corresponding to H18 of B domain of Protein A or Protein Z has been substituted with a Serine in all the monomers in the multimeric ligand.

7. The method of claim 1 , wherein the ligand provides an increase in elution pH by at least 0.2 compared to non-substituted ligand.

8. The method of claim 1 , wherein the ligand provides an increase in elution pH by at least 0.4 compared to non-substituted ligand.

9. The method of claim 1 , wherein the ligand provides an increase in elution pH to at least 4.0 while the yield of target molecule is at least 80% or preferably >95%.

10. The method of claim 1 , wherein the ligands have affinity for the Fc part of an immunoglobulin but lack affinity for the Fab part of an immunoglobulin.

11. The method of claim 1 , wherein a glycine residue corresponding to position 29 of the B domain of Protein A has been changed to an alanine.

12. The method of claim 1 , wherein the ligands achieve alkali stability by mutating at least one asparagine residue to an amino acid other than glutamine.

13. The method of claim 12 , wherein the ligand is Protein Z in which the alkali-stability has been achieved by mutating at least one asparagine residue to an amino acid other than glutamine.

14. The method of claim 13 , wherein the alkali-stability of Protein Z has been achieved by mutating at least the asparagine residue at position 23 to an amino acid other than glutamine.

15. The method of claim 5 , wherein said multimer is a dimer.

16. The method of claim 5 , wherein said multimer is a tetramer.

17. The method of claim 1 , wherein the immunoglobulin containing protein is a monoclonal antibody.

18. The method of claim 1 , wherein the immunoglobulin containing protein is a polyclonal antibody.

19. The method of claim 1 , wherein the immunoglobulin containing protein is a fusion protein containing an immunoglobulin Fc Portion fused with another protein.

20. A ligand comprising one or more domains (monomers) of staphylococcal Protein A (SpA) (E, D, A, B, C) or protein Z or a functional variant thereof, wherein in at least one of the monomers, the Asparagine or Histidine at a position corresponding to H18 of B domain of Protein A or Protein Z has been substituted with a Serine.

21. A matrix for affinity separation comprising the ligand of claim 20 coupled to a solid support.

22. The matrix of claim 21 , wherein the solid support is polysaccharide based.

23. The matrix of claim 21 , wherein the ligands are coupled via thioether bonds.

24. The method of claim 1 , wherein a pH gradient elution is performed which results in an efficient separation of aggregate and monomer species of the target.

25. The method of claim 1 , wherein the ligand provides an increase in elution pH to at least 4.2 while the yield of target molecule is at least 80% or preferably >95%.

26. A method of separating one or more immunoglobulins containing proteins from a liquid, which method comprises:

(a) contacting the liquid with a separation matrix comprising ligands immobilized to a support;

(b) allowing said immunoglobulin containing proteins to adsorb to the matrix by interaction with the ligands;

(c) an optional step of washing the immunoglobulin containing protein adsorbed matrix;

(d) recovering said immunoglobulin containing proteins by contacting the matrix with an eluent which releases the proteins;

the improvement being that each of said ligands comprises one or more monomeric domains of staphylococcal Protein A (SpA) (B, C) or Protein Z,

wherein in at least one of the one or more monomers, the Histidine at position H18 has been substituted with a Serine, and

wherein the ligand provides an increase in elution pH compared to non-substituted ligand with essentially unaltered or improved dynamic binding capacity and yield.