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Cellular and Molecular Basis of Human Biology
Published in Lawrence S. Chan, William C. Tang, Engineering-Medicine, 2019
These mobile proteins are the products of committed B-cells, plasma cells. In human, 5 classes of antibodies are produced: IgM, IgG, IgA, IgE, and IgD. These classes of antibodies are immunologically distinguished by the difference of their heavy chain sequences. As for light chain, only two classes are produced, lambda and kappa chains. In human, IgG has 4 subclasses, IgG1, IgG2, IgG3, and IgG4; whereas IgA has 2 subclasses, IgA1 and IgA2. IgD is a B cell surface receptor and is not usually released into the extracellular environment. Whereas IgM is the initially released antibody response, IgG comes later in the immune response but become the dominant class, constituting 80% of circulating antibodies. IgA is primarily responsible for mucosal immune defense. IgE involves in allergic reaction by binding on IgE receptors of mast cells, triggering mast cells to release histamines.
Recombinant Antibodies for Diagnostic Applications: Design Considerations and Structural Correlates
Published in Richard O’Kennedy, Caroline Murphy, Immunoassays, 2017
Stephen Hearty, Richard O’Kennedy
Camelids (camels, llamas and alpacas) produce a class of ‘heavy chain only’ antibodies in which binding is mediated through unpaired variable heavy domains termed ‘VHH’ [31]. Whereas conventional human and mouse V domains are stabilised by heterodimerisation, VHH domains are characterised by a series of hallmark substitutions [32] which confer increased hydrophilicity in the region corresponding to the site of light chain heterodimerisation in conventional IgG. This translates into improved soluble expression, a feature which renders libraries of VHH domain’s a very efficient means of harnessing and mining natural and synthetic camelid antibody diversity.
Glossary of scientific and technical terms in bioengineering and biological engineering
Published in Megh R. Goyal, Scientific and Technical Terms in Bioengineering and Biological Engineering, 2018
Antibody structure are antibodies with a well-defined structure. Each antibody has two identical “light” chains and two identical “heavy” chains. Each chain comprises a constant region, and a variable region.
Cytoplasmic and periplasmic expression of recombinant shark VNAR antibody in Escherichia coli
Published in Preparative Biochemistry and Biotechnology, 2019
Herng C. Leow, Katja Fischer, Yee C. Leow, Katleen Braet, Qin Cheng, James McCarthy
The evolution of immunoglobulins from invertebrates began ∼550 million years ago.[1] With the emergence of antibody surface display technology, interest has increased in new binders from less commonly used animals, including Variable domains of heavy chain-only (VHH) from camelids, and variable new antigen receptors (VNAR) from sharks. The unusual antibodies derived from these groups of animals have been reported to provide promising specificity and sensitivity for target antigens[2] As in all mammals, members of the camelid family produce immunoglobulins G that contains only a heavy chain domain. Owing to its peculiar structure, this antibody has been configured as “heavy chain only” antibodies (HCAbs).[3] HCAbs are slightly different from IgG, in that they also include both a constant (Fc) and a variable domain. The isolated variable domain region of camelids HCAbs is known as VHH (variable domain of the heavy chain of HCAbs) or Nanobody® (Nb; Ablynx).[4]
Construction and evaluation of wild and mutant ofatumumab scFvs against the human CD20 antigen
Published in Preparative Biochemistry & Biotechnology, 2023
Reza Maleki, Azam Rahimpour, Masoumeh Rajabibazl
One of the smallest structural and functional fragments are single chain variable fragments having parental molecule's antigen-binding ability. These molecules are made up of an antibody's variable light () and variable heavy () chains connected by a flexible polypeptide linker.[10,11] Having about 25-30 kDa molecular weight, scFvs provide numerous therapeutic benefits compared to whole antibodies. For example, they represent an improved tissue penetration and dispersion in addition to accelerated removal from blood circulation.[12] Using scFvs, it is possible to target a certain molecule on malignant cells and either neutralize the targeted protein or effectively deliver a specific therapeutic chemical. In fact, these antibody fragments can be generated as fusions with cytotoxic agents, radionuclides, or drugs and performed as therapeutic agents.[13,14] Recently, we developed Four mutated variants of ofatumumab as well as the non - modified antibody. Antigen binding properties of isolated antibodies to CD20 antigen were shown to be significantly improved in one of the mutants when compared to the wild type.[15] We produced a recombinant anti-CD20 scFv from variant 3 mutation and wild type of Ofatumumab antibody. Recombinant scFvs were created by a short polypeptide linker joining the and domains and subsequently, affinity calculation was performed. Moreover, the ability of pure scFvs to bind to CD20 antigen and also affect cell viability was evaluated in the B lymphocyte Raji cell line.