Complement factor based affinity chromatography

A fusion polypeptide according to formula I

• TAG-X1-C1qA-X2-C1qB-X3-C1qC-X4 (formula I)
• wherein
• X1 denotes a first peptidic linker,
• X2 denotes a second peptidic linker,
• X3 denotes a third peptidic linker,
• X4 denotes a fourth peptidic linker,
• X1, X2, X3, X4 are independently of each other either present or absent,
• TAG is an amino acid sequence tag,
• TAG can be present or absent,
• C1qA is a fragment of SEQ ID NO:
• 01,
• C1qB is a fragment of SEQ ID NO:
• 03,
• C1qC is a fragment of SEQ ID NO:
• 05, and
• - denotes a peptide bond.