Patent ID: 7033798

Claim:
A method for stabilizing a chimeric immunoglobulin or immunoglobulin fragment (chimera) that comprises i) VH domain antigen-binding loops from a donor immunoglobulin or immunoglobulin fragment (donor) which is able to bind to an antigen, and ii) VH domain framework regions from an acceptor immunoglobulin or immunoglobulin fragment (acceptor), wherein the VH domains of said donor and of said acceptor belong to different framework structure subgroups, and wherein said method comprises the step of replacing in the chimera one or more of the residues present at identified framework positions in the acceptor by those present at corresponding positions in the donor, wherein different amino acid residues present in said acceptor and said donor at one or more of said identified framework positions lead to the formation of different framework structure subgroups, wherein said identified framework positions are selected from the group consisting of H6, H7, H8, H9, H10, H18, H20, H38, H63, H67, H82 and H109 in said VH domains, wherein a stabilized antigen-binding immunoglobulin or immunoglobulin fragment is established, and wherein said chimera is able to bind to said antigen.