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Updated: Jan 30, 2026

Determining Binding Affinity KD of Radiolabeled Antibodies to Immobilized Antigens
Published on: June 23, 2022
Binding to nanopatterned antigens is dominated by the spatial tolerance of antibodies
Alan Shaw1, Ian T Hoffecker1, Ioanna Smyrlaki1
1Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
Although repetitive patterns of antigens are crucial for certain immune responses, an understanding of how antibodies bind and dynamically interact with various spatial arrangements of molecules is lacking. Hence, we introduced a new method in which molecularly precise nanoscale patterns of antigens are displayed using DNA origami and immobilized in a surface plasmon resonance set-up. Using antibodies with identical antigen-binding domains, we found that all the subclasses and isotypes studied bind bivalently to two antigens separated at distances that range from 3 to 17 nm. The binding affinities of these antibodies change with the antigen distances, with a distinct preference for antigens separated by approximately 16 nm, and considerable differences in spatial tolerance exist between IgM and IgG and between low- and high-affinity antibodies.
Although repetitive patterns of antigens are crucial for certain immune responses, an understanding of how antibodies bind and dynamically interact with various spatial arrangements of molecules is lacking. Hence, we introduced a new method in which molecularly precise nanoscale patterns of antigens are displayed using DNA origami and immobilized in a surface plasmon resonance set-up. Using antibodies with identical antigen-binding domains, we found that all the subclasses and isotypes studied bind bivalently to two antigens separated at distances that range from 3 to 17 nm. The binding affinities of these antibodies change with the antigen distances, with a distinct preference for antigens separated by approximately 16 nm, and considerable differences in spatial tolerance exist between IgM and IgG and between low- and high-affinity antibodies.
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