Figure 1: Schematic overview of a typical mammalian Ig antibody.
A group of antibody variants fulfilling these requirements are Nanobodies. Nanobodies are antibodies consisting of only the heavy chain, they are naturally found in the sera of camelids (so called “single variable domain on a heavy chain or “VHH”) and of cartilaginous fish (so called “variable new antigen receptor (VNAR) single domain antibodies). VHH antibodies are only around 15 kDa and thus better suited for scientific and medical application than normal Ig antibodies –. Another group of antibody-variants are single chain variable fragments (scFv). In this approach the VH and the VL domains are linked by a short peptide linker, thus creating a significantly smaller binding fragment which does not need glycosylation. Furthermore scFv´s are a single polypeptide and not several chains held together via disulfide bonds, an advantage they have in common with Nanobodies .