Author Archives: Guido Strohlein

Purification of Antibody Fragments with Amsphere™ A3 Protein A Resin

The binding mechanism between the engineered C domain of the Amsphere™ A3 protein A (PrA) ligand and a VHH single domain antibody (sdAb) was revealed. Binding sites in the PrA ligand in helices 2 and 3 and in framework regions 1 and 3 of the VHH were confirmed. Identified VHH residues are not involved in antigen recognition. Overlap with a human VH showed the same interaction sites. These results provide insight on why Amsphere A3 is a suitable tool for…

Purifying Common Light-Chain Bispecific Antibodies

A bispecific antibody can bind two different antigens. Immunoglobulin G (IgG) type antibodies have two binding sites with different variable regions. An IgG variable region is made up of a variable light-chain sequence (VL) and a variable heavy-chain sequence (VH). The light chains (LCs) of common LC antibodies are identical for both variable regions, leaving the heavy chain (HC) for generating different specificities. Thus, recombinant host cells for production of common LC bispecific antibodies carry genes for both HCs, with…