Antibody
is not a stranger to everyone, even a new born baby. It is the black hole on
the biological world, as there is always something new that attracts biologists
and researchers.
Since
the first success achieved in single chain antibody fragment(scFv)research by Bird and Huston in the 1988, tremendous achievements
have been made in the research and development of single chain antibody
technology.
However,
in terms of application, there are still problems remain unsettled. The
scFv fragments derived from phage display antibody libraries usually have short
half-life and less affinity. However, multivalency of antibody
molecules turns out to be a desirable property in many in vitro and in vivo
applications. After years of experience and great efforts, scientists and
researchers from Creative Biolabs
have carried out a series of approaches for bivalent and bispecific scFv and
Fab construction, which may greatly contribute to the current situation. (Bivalent and Bispecific scFv/Fab)
According
to its newest data, there are three approaches of generating genetically
engineered and dimerized scFv antibody fragments, miniantibody, diabody and
Tandem scFv.
Figure
1. Schematic diagram of bispecific antibody
Miniantibody
Bivalent
or bispecific (scFv) 2, the so-called miniantibody, is produced by the
combination of two scFv molecules with two modified dimerization domains.
Leucine zippers are utilized to mediate dimerization of scFv in a miniantibody
form. It constructed dimerization cassettes which allow the conversion of scFv
antibodies from all its phage display libraries to bivalent or bispecific
antibodies. During this procedure, either Fos or Jun leucine zippers are fused to
scFv proteins. Two cysteine residues were engineered in the Fos and Jun zipper
domains to produce disulfide-stabilized homodimers, which usually leads to
efficient production of stable, secreted homodimers that are able to retain
their specificity as assessed in a number of assays.
Diabody
Diabody
is a non-covalent dimer of single-chain scFv, fragments that consists of the
heavy chain variable (VH) and light chain variable (VL) regions connected by a
small peptide linker. 14–15 amino acid residues’ common linkers are long enough
to span the distance between the N- termini and C-termini of the variable
domains in a scFv. However, utilizing linkers of 3–12 amino acid residues in
length can lead to the formation of diabody.
When two ScFvs linked with the short linkers are expressed in the same cells, dual-functional antigen-binding sites will be formed through crossover pairing of the variable light-chains and heavy-chains. The bi-specific diabody, which is constructed with heterogeneous scFvs, is also an important and commonly used form of recombinant bi-specific antibody. A distinct feature of diabody is that it has a rigid structure and can be expressed at high yields in bacteria. See figure 2.
It is worth mentioning here that bispecific T cell engager (BiTE) is a unique form of tandem scFv. In a BiTE molecule, one of the scFvs binds to T cells via CD3 receptor and the other to a tumor cell via a tumor specific molecule. As this procedure brings together the T cell and cancer cell, it has great possibilities in cancer therapy. (BiTE). See figure 2.
Tandem scFv
Tandem
scFv (taFv) is produced by connecting two scFv molecules with a short linker.
This form of scFv has a very flexible structure and is comparatively easy to be
generated. Both bacterial expression and refolding and eukaryotic expression
are able to produce tandem scFvs. With years of experiences, Creative Biolabs
has successfully constructed over 100 tandem scFvs.
Figure 2. Schematic diagram of
Diabody and Tandem scFv
About Creative Biolabs
Creative
Biolabs is a professional biotech service provider. Since been established in the
year of 2005, it has been focused on the research and development of single
chain antibody technology. Learn more about Creative
Biolabs.
Thanks for sharing the information related solving SCFV problems.
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