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Biorecognition Elements in Biosensors
Published in Sibel A. Ozkan, Bengi Uslu, Mustafa Kemal Sezgintürk, Biosensors, 2023
Michael López Mujica, Alejandro Tamborelli, Virginia Vaschetti, Pablo Gallay, Fabrizio Perrachione, Daiana Reartes, Rocío Delpino, Marcela Rodríguez, María D. Rubianes, Pablo Dalmasso, Gustavo Rivas
Antibodies appeared in the scenario of biosensors in the 80s as a powerful tool for the development of immunosensors. Antibodies (Ab) or immunoglobulins (Ig) are produced in eukaryotes as a response to an antigen, which is any agent foreign to the organism (11). They are large glycoproteins of molecular weight around 150 kDa, that possess four chains, two small “light” polypeptide chains with an approximate molecular weight of 25 kDa each, and two large “heavy” polypeptide chains of 50 kDa each (12). These four chains are bound by disulfide bonds and form a Y-shape, as shown in Figure 5.4. They possess two distinct regions, the fragment crystallizable region (Fc fragment), which interacts with cell surface receptors and activates other immune system partners, and the antigen-binding region (Fab fragment) that recognizes and binds to antigens through a specific recognition domain called antigen determinant or epitope (12). The sequence of the amino-acids of these N-terminal ends determines the specific antigen-binding properties of the molecule. The complementary site on the antibody is called paratope. Binding interactions between antigen and antibody involve relatively weak noncovalent forces (electrostatic, hydrophobic, hydrogen bonding, and van der Waals interactions) (11–12).
Hybrid System by AINFS and AINFNNS for Robust Control of Nonlinear System
Published in Dong Hwa Kim, Tuning Innovation with Biotechnology, 2017
The antibody molecule acts as a bridge between the cytotoxic cell and the target cell, subsequently causing the target cell to activate through a receptor. Antibodies are actually three-dimensional Y shaped molecules which consist of two types of protein chain: light and heavy. They also possess two paratopes which represent the pattern used to match the antigen. The regions on the molecules that the paratope can attach to are called epitopes. The molecules with antigenic peptide bound to them will be responsible for the interaction with T-cell receptors. The site that interacts with a T-cell receptor on an antigenic peptide is called epitode [225, 226].
Immune Systems, Molecular Diagnostics, and Bionanotechnology
Published in Anil Kumar Anal, Bionanotechnology, 2018
Antigen–antibody interaction occurs between the epitope, small restrict particles on the surface of antigens and paratope, which is the site on the antibody where the antigen binds. Antibodies synthesized against antigens can identify surface epitopes, which represent conformational structures. On account of this ability, antibodies exhibit specificity, and therefore can differentiate between two closely related antigens or can bind to divergent antigens with similar epitopes (cross-reactivity) (Schroeder and Cavacini 2010).
Preparation monoclonal β-type anti-idiotype antibody of zearalenone and development of green ELISA quantitative detecting technique
Published in Preparative Biochemistry & Biotechnology, 2020
Luhuai Shi, Tao Yu, Miner Luo, Hong Wang
In the recent years, many institutions have focused on developing substitutes for small molecular hapten (toxins) in order to establish a green detection method. It is similar to using anti-idiotype antibodies or anti-idiotypic variable domain of heavy chain (VHH) to simulate cortisol, aflatoxin or zearalenone[14–16]. The conception of the anti-idiotype antibody was presented in an immunological network theory by N. K. Jerne 1974, where specific antibodies were used to find variable regions of antibodies in vivo[17–20]. α-Type(Ab2α) and β-type anti-idiotype antibodies (Ab2β) were commonly employed by many immunological assays. Ab2α can recognize idiotypes distal from the antigen binding site and does not interfere with antigen binding. Ab2β bind within the paratope, can mimics the configuration of the original antigen and be used as the antigen surrogate.