Tetrafluorophenyl (TFP) esters are an improvement over the succinimidyl ester (SE or NHS-ester) chemistry typically used to attach fluorophores or haptens to the primary amines of biomolecules. Both reactive chemistries produce the same strong amide bond between the dye or hapten and the compound of interest, but TFP esters are less susceptible to spontaneous hydrolysis during conjugation reactions. Alexa Fluor TFP esters are stable for several hours at the basic pH typically used for reactions – far outlasting succinimidyl esters.
For Research Use Only. Not for use in diagnostic procedures.
Store in freezer (-5 to -30°C) and protect from light.
Frequently asked questions (FAQs)
I am labeling a protein with Alexa Fluor 488 SDP ester. The manual recommends using a sodium bicarbonate buffer at pH 8.3. Can I use a different buffer instead?
Yes. The important thing is to use a buffered solution with a pH between 8.0 and 8.5. Do not use Tris buffer, which has amine groups. Most other buffers will work fine in that pH range. This is also true for other amine-reactive dyes, such as succinimidyl (NHS) esters or TFP esters.
I am not going to use all of my Alexa Fluor succinimidyl ester reactive dye. Can I just make it up in DMSO and store aliquots at -20 degrees C?
This is not recommended. Any trace amounts of water in the DMSO can promote spontaneous hydrolysis over time. Even if using anhydrous DMSO, DMSO is hygroscopic; it readily absorbs moisture from the atmosphere over time. A better alternative is to dissolve the reactive dye in a volatile solvent, make smaller aliquots and then evaporate off the solvent using a vacuum pump. The smaller aliquots of solid reactive dye should then be stored frozen, desiccated and protected from light. Contact Technical Support by sending an email to techsupport@thermofisher.com for the recommended volatile solvent.