Selective enrichment of antibodies

Abstract

The invention relates to a process for the selective concentration of immunoglobulins or other proteins that contain an Fc domain (target protein), comprising the following steps: a. preparing a solution that contains the target protein; b. incorporating an Fc-binding protein with precisely two binding sites under conditions that allow binding to occur; c. separating the precipitate from the liquid phase; d. undoing the binding of the target protein from the Fc-binding protein.

1 . Process for the selective concentration of immunoglobulins or other proteins that contain an Fc domain (target protein), comprising the following steps:
 a. preparing a solution that contains the target protein;   b. incorporating an Fc-binding protein with precisely two binding sites under conditions that allow binding to occur;   c. separating the precipitate from the liquid phase;   d. undoing the binding of the target protein from the Fc-binding protein.   
     
     
         2 . Process according to  claim 1 , wherein the Fc-binding protein is a dimer of an Fc-binding domain of protein A or protein G. 
     
     
         3 . Process according to  claim 2 , wherein the Fc-binding domain comprises or contains one of the sequences SEQ ID NO: 1 to SEQ ID NO: 11. 
     
     
         4 . Process according to  claim 2 , wherein the two monomers of the dimer are linked together by a disulphide bridge. 
     
     
         5 . Process according to  claim 1 , wherein the dimer is a homodimer, the monomers of which have the sequence SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, or a sequence that differs from SEQ ID NO. 1 in 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 amino acids. 
     
     
         6 . Process according to  claim 1 , wherein the Fc-binding protein is used in a molar ratio of 0.5-20 in relation to the target protein. 
     
     
         7 . Process according to  claim 1 , wherein the solution in step a. has a pH of 5.5-9. 
     
     
         8 . Process according to  claim 7 , wherein the solution in step a. has a pH of 6-8. 
     
     
         9 . Process according to  claim 1 , wherein the undoing of the binding in step d. takes place at a pH of 2-4.5. 
     
     
         10 . Fc-binding protein that consists of 2 identical sub-units that have the sequence SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, or a sequence that differs from SEQ ID NO. 1 in 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 amino acids, wherein the two sub-units are linked together via a covalent bond. 
     
     
         11 . Fc-binding protein according to  claim 10 , wherein the covalent bond is a disulphide bond.