Immunoactive two-dimensional self-assembly of monoclonal antibodies in aqueous solution revealed by atomic force microscopy.
The conformational flexibility of antibodies in solution directly affects their immune function. Namely, the flexible hinge regions of immunoglobulin G (IgG) antibodies are essential in epitope-specific antigen recognition and biological effector function. The antibody structure, which is strongly related to its functions, has been partially revealed by electron microscopy and X-ray crystallography, but only under non-physiological conditions. Here we observed monoclonal IgG antibodies in aqueous solution by high-resolution frequency modulation atomic force microscopy (FM-AFM). We found that monoclonal antibodies self-assemble into hexamers, which form two-dimensional crystals in aqueous solution. Furthermore, by directly observing antibody-antigen interactions using FM-AFM, we revealed that IgG molecules in the crystal retain immunoactivity. As the self-assembled monolayer crystal of antibodies retains immunoactivity at a neutral pH and is functionally stable at a wide range of pH and temperature, the antibody crystal is applicable to new biotechnological platforms for biosensors or bioassays.
Department of Electronic Science and Engineering, Kyoto University, Kyoto University Katsura, Nishikyo, Kyoto 615-8510, Japan.
Shinichiro
S
Ido
Device Solutions Center, Panasonic Corporation, Yagumo-naka-machi 3-1-1, Moriguchi, Osaka 570-8501, Japan.
Hirokazu
H
Kimiya
1] Department of Electronic Science and Engineering, Kyoto University, Kyoto University Katsura, Nishikyo, Kyoto 615-8510, Japan [2] The Hakubi Center for Advanced Research, Kyoto University, Kyoto University Katsura, Nishikyo, Kyoto 615-8520, Japan.
Kei
K
Kobayashi
Department of Electronic Science and Engineering, Kyoto University, Kyoto University Katsura, Nishikyo, Kyoto 615-8510, Japan.
Hiroaki
H
Kominami
Department of Electronic Science and Engineering, Kyoto University, Kyoto University Katsura, Nishikyo, Kyoto 615-8510, Japan.
Kazumi
K
Matsushige
Department of Electronic Science and Engineering, Kyoto University, Kyoto University Katsura, Nishikyo, Kyoto 615-8510, Japan.
Hirofumi
H
Yamada
D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry*; D003460:Crystallization; D006863:Hydrogen-Ion Concentration; D051379:Mice; D018625:Microscopy, Atomic Force / Q000379:methods*; D012996:Solutions; D013696:Temperature; D014867:Water / Q000737:chemistry
D000911:Antibodies, Monoclonal; D012996:Solutions; D014867:Water