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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
Some special antibodies called single-domain antibodies, also known as nanobodies, are derived from heavy-chain antibodies (HCAbs), which are naturally present in all camelidae. These animals produce HCAbs in their serum, lacking Fc fragments and a canonical constant heavy chain 1 (CH1) domain in the heavy chain (17). These HCAbs are shown in Figure 5.5 and have an antigen recognition part composed of single variable domains, known as the variable domain of the heavy chain of heavy-chain antibody (VHH). Nanobodies are considered the smallest intact antigen-binding fragments (molecular weight of approximately 12–15 kDa). They are robust, resistant to denaturation/thermal degradation, easy to manipulate with aqueous solubility, and capable of reducing steric hindrance and recognizing inaccessible and cryptic epitopes (18–20).
Pharmaceutical Applications of Albumin
Published in Amit Kumar Nayak, Md Saquib Hasnain, Dilipkumar Pal, Natural Polymers for Pharmaceutical Applications, 2019
Another approach is to use albumin binding antibody. Camelid antibodies constructed of heavy-chain antibody fragments containing a single variable domain (VHH) and two constant domains (CH2 and CH3). The VNH domain is highly targeted specific and binds with their antigen target with high specificity and low viscosity in comparison to single chain anti-bodies. One example of camelid is murine trivalent antibodies that were constructed to bind HSA on the one hand and the murine or human tumor necrosis factor-α (TNF-α) on the other.
COVID-19;-The origin, genetics,and management of the infection of mothers and babies
Published in Egyptian Journal of Basic and Applied Sciences, 2020
Hassan Ih El-Sayyad, Yousef Ka Abdalhafid
Camelids, such as alpacas and llamas are of medical importance due to producing a novel type of heavy chain-antibody specific for production single domain antibodies which are highly selective for different protein antigen. The extracted single domain antibodies can then be used either directly or as part of an engineered reagent. Single domain antibodies can be generated, purified, and directly used in prokaryotic expression system in large quantities as recombinant proteins or can be engineered to contain unique markers as reporters in cellular studies or in diagnostics [148]. During invasion of the human cells, the SARS-CoV-2 receptor-binding domain (RBD) of the spike protein binds to ACE2 receptor. Two nanobodies, H11-D4 and H11-H4, are created with high selective binding to BRD and block their crosslink their ACE2 after application of a naïve IIama single-domain antibody library and PCR-based maturation. The studies illustrate that nanobodies identify the same epitope, which overlaps with the ACE2-binding surface, illustrating the blocking of the RBD-ACE2 interaction [149].
Generation and evaluation of anti-mouse IgG IgY as secondary antibody
Published in Preparative Biochemistry & Biotechnology, 2020
Qi Zhang, Dongyang He, Long Xu, Shikun Ge, Jinquan Wang, Xiaoying Zhang
The current mainstream technologies of antibody engineering are IgG generation based on hybridoma technology and genetic engineering technology. However, different antibody generation strategies may still be of interest and useful, and different animal classes indeed provide different mechanisms and possibilities for antibody generation. For example, poultry are particularly suitable for the production of antibody against highly conserved proteins from mammalian systems. Also, the variable domains of heavy chain antibody (VHH) derived from camelids are more likely to penetrate the tissues and membranes due to their small size and low molecular weight, and this may result in more effective intracellular therapeutic/diagnostic applications.[13]
Nanobodies targeting the interaction interface of programmed death receptor 1 (PD-1)/PD-1 ligand 1 (PD-1/PD-L1)
Published in Preparative Biochemistry & Biotechnology, 2020
Biyan Wen, Lin Zhao, Yuchu Wang, Chuangnan Qiu, Zhimin Xu, Kunling Huang, He Zhu, Zemin Li, Huangjin Li
Antibodies lacking the light chain exist in the peripheral blood of camels, leaving only the heavy chain variable region (VHH) and two conventional CH2 and CH3 regions.[16] The recombinant VHH shows structural stability and equivalent binding activity comparable to the original heavy chain antibody, and is the smallest unit currently known to bind the target antigen. VHH has a molecular weight of 12 ∼ 15 kDa and a disulfide bond between framework regions 1 (FR1) and FR3. Its CDR3 region is longer than that of conventional antibodies and mediates antigen recognition and binding. Its size is nanoscale (∼2.5 nm diameter × 4 nm height) and is termed a nanobody. Compared to traditional monoclonal antibodies, nanobodies have low molecular weights and display high stability, tissue penetration, and weak immunogenicity.[17] The advantages of these nanobodies make them ideal candidates for low-cost treatments, and a nanobody against PD-L1, KN035, was clinically developed by Alphamab.[18] At present, nanobodies against PD-1 or PD-L1 were usually screened with the extracellular domains of the target molecules as the antigens from the immunized alpaca-derived phage display library. However, such strategies for targeting molecular surfaces are less efficient at screening small molecule nanobody blockers. Targeting the interaction interface is an ideal strategy to block protein-protein binding. In our laboratory, a series of nanobodies targeting the dimerization of the epidermal growth factor receptor (EGFR) were obtained from a humanized nanobody phage display library using a peptide derived from the dimerization interface as the antigen, which could effectively inhibit the growth of EGFR-overexpressing tumor cells in a manner comparable to mAbs.[19,20] In this study, the feasibility of targeting interaction interface strategies for screening PD-1/PD-L1 nanobody blockers was explored by using the peptide PD-1125–136 located at the interaction interface as the antigen to screen nanobodies from a synthetic library, laying the foundation for screening the clinically valuable nanobodies from the immunized alpaca-derived phage display library.