Version 1
: Received: 10 October 2024 / Approved: 11 October 2024 / Online: 11 October 2024 (14:20:11 CEST)
How to cite:
Yazaki, S.; Komatsu, M.; Dong, J.; Ueda, H.; Arai, R. Crystal Structures of Antigen-Binding Fragment (Fab) of Anti-Osteocalcin Antibody KTM219: Structural Basis for Quenchbody (Q-body). Preprints2024, 2024100901. https://doi.org/10.20944/preprints202410.0901.v1
Yazaki, S.; Komatsu, M.; Dong, J.; Ueda, H.; Arai, R. Crystal Structures of Antigen-Binding Fragment (Fab) of Anti-Osteocalcin Antibody KTM219: Structural Basis for Quenchbody (Q-body). Preprints 2024, 2024100901. https://doi.org/10.20944/preprints202410.0901.v1
Yazaki, S.; Komatsu, M.; Dong, J.; Ueda, H.; Arai, R. Crystal Structures of Antigen-Binding Fragment (Fab) of Anti-Osteocalcin Antibody KTM219: Structural Basis for Quenchbody (Q-body). Preprints2024, 2024100901. https://doi.org/10.20944/preprints202410.0901.v1
APA Style
Yazaki, S., Komatsu, M., Dong, J., Ueda, H., & Arai, R. (2024). Crystal Structures of Antigen-Binding Fragment (Fab) of Anti-Osteocalcin Antibody KTM219: Structural Basis for Quenchbody (Q-body). Preprints. https://doi.org/10.20944/preprints202410.0901.v1
Chicago/Turabian Style
Yazaki, S., Hiroshi Ueda and Ryoichi Arai. 2024 "Crystal Structures of Antigen-Binding Fragment (Fab) of Anti-Osteocalcin Antibody KTM219: Structural Basis for Quenchbody (Q-body)" Preprints. https://doi.org/10.20944/preprints202410.0901.v1
Abstract
Quenchbody (Q-body), a new type of fluorescent immunosensor, is an antibody fragment labeled with a fluorescent dye. When Q-body binds to its antigen, the fluorescence intensity increases. Highly sensitive detection of antigens by changes in fluorescence intensity is performed in a single step by mixing sample and reagent. In this study, to reveal the structural basis for Q-body, we solved the crystal structures of antigen-binding fragment (Fab) of an anti-osteocalcin antibody KTM219, which is applicable to Q-body, and its complex with the antigen osteocalcin C-terminal peptide (BGP-C7). Also, we solved the structure of a KTM219 Fab crystal grown in the presence of a fluorescent dye 5(6)-carboxytetramethylrhodamine (TAMRA), however, a tightly bound TAMRA was not found in the electron density map. We predicted the binding site of TAMRA by docking simulations. These results support the structural basis for the Q-body mechanism as follows. In the absence of the antigen, the fluorophore located near tryptophan residues is quenched in the hydrophobic pocket of the antigen binding site between VH and VL. In association with the competitive binding of the antigen, the fluorophore is released from the antigen binding pocket and emits fluorescence. The crystal structures of KTM219 Fab and the structural basis of Q-body would be useful for further development and improvement of Q-body fluorescent immunosensors.
Biology and Life Sciences, Biochemistry and Molecular Biology
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
