These products were developed by our partner company NanoTag Biotechnologies.
Camelid single domain antibodies (sdAbs) consist only of one antigen binding site of an Alpaka heavy chain antibody. With only ~15 kDa, these Tags are about 10-times smaller than conventional IgG antibody molecules. A large panel of different conjugates like chemical fluorophores, biotin or DBCO extends the range of applications from fluorescence detection over pull-downs and westernblots to click-chemistry based methods.
FluoTag® is NanoTag’s trademark for camelid single-domain antibodies conjugated to chemical fluorophores.
Three variants of FluoTags® are available, the -Q, -X2 and -X4 series:
In FluoTag-Q® each fluorophore is coupled to exactly one FluoTag, which in turn binds to its target molecule in a monovalent fashion. The high binding affinity and a coupling efficiency of > 95% guarantees a highly linear relation between the number of target molecules and the intensity of fluorescence. This enables a direct count of the target molecule of interest. Its small size ensures excellent tissue penetration properties. The fluorophore is located exceptionally close to the recognized epitope (< 1.5 nm), which is ideal for all microscopy techniques.
FluoTag-X2® reagents are composed of a single sdAb carrying two fluorophores per protein molecule. The conjugate is therefore up to 2-fold (“X2”) brighter than the corresponding FluoTag®-Q product. The maximal displacement of fluorophores from the antigen-binding surface is ~3 nm. FluoTag®-X2 reagents are only slightly larger than the corresponding FluoTag®-Q products and therefore show similarly good tissue penetration features.
Each FluoTag-X4® reagent is a blend of two different sdAbs FluoTag®-X2 molecules that independently bind the target protein. As each sdAb carries two fluorophores per protein molecule, the blend can direct up to 4 fluorophores to each target protein. The reagent is therefore up to 4-fold brighter ("X4") than the corresponding FluoTag®-Q products. The maximal displacement of fluorophores from each antigen-binding surface is ~3 nm. FluoTag®-X4 reagents have the same size as the corresponding FluoTag®-X2 products and therefore show similarly good tissue penetration features.
In comparison to detection systems using conventional antibodies, FluoTag-X can thus improve the localization accuracy by 10-15 nm. Both features - superior brightness and precise fluorophore placement - render the FluoTag-X products excellent tools for all microscopy techniques.
Selector resins are affinity resins based on controlled immobilization of single-domain antibodies.
For production, high-quality agarose resins are functionalized in-house using propriety chemistry. This results in both a highly specific, stable, and oriented sdAb attachment and an ultra-low non-specific background binding.
The precise and oriented chemistry also ensures optimal functionality and accessibility of the sdAbs and therefore results in beads with a high capacity.
