Frequently asked questions
A FluoTag is a dye conjugated alpaca single-domain antibody (sdAb), also referred to as VHH or nanobody (nanobody is a trademark of Ablynx). It is in the range of 15 kDa and ~3 nm in molecular weight and size respectively. This means that sdAbs are ten times lighter and up to 5x smaller than a conventional IgG molecule. Our FluoTags can position a fluorophore up to 20 nm closer to the intended target than using conventional primary-secondary antibody complex detection.
In our FluoTag-Q series, a single fluorophore is coupled to exactly one FluoTag (sdAb), which in turn binds to its target molecule in a monovalent fashion (therefore the signals obtained with our FluoTag-Qs are typically linear to amount of target protein). The FluoTag-X2 series features 2 site-specifically conjugated fluorophores per sdAb, which results in enhanced image brightness when compared to FluoTag-Q. The FluoTag-X4 series, corresponds to a blend of 2 different FluoTags that bind at different epitopes of the same target protein. Each FluoTag bears 2 site-specifically coupled fluorophores, therefore, the Fluotag-X4 bring up to 4 fluorophores to your protein of interest increasing the integrated signal per target molecule.
Especially for the fluorophores absorbing at 488 nm it is sometimes hard to see a colour by eye on the tube. We carefully remove uncoupled dye from our products to minimize dye related background in your sample. Our method to site-specific conjugate dyes to our FluoTags allows us to closely monitor the FluoTag to dye ratio and thus always make sure you get the best quality probe as possible.
Yes, we offer custom labelings at very affordable rates, since we are always curious to know which dye is “hot” right now in the scinetific community. Besides dyes we also offer to conjugate biotin, desthiobiotin, DBCO or other molecules. Just give us a call or send us an email telling us what do you want to do with our Tags!
Yes, we offer all the nanobodies we produce also uncoupled. You can chose the position of the ectopic cysteine (N-terminal, C-terminal or both ends) for doing maleimide conjugations. Please note that we only ship unconjugated nanobodies for maleimide labeling on dry-ice to preserve the reactivity of the probe. We can also help you on how to make the best of your conjugation reaction.
Yes, we have done long term test to guarantee that our products survive shipping at ambient temperatur. However, we recommend freezing the FluoTags upon arrivial to extend thier funtional life. This way we can avoid unnecessary high shipping costs.