The Twinkle Factory launches tfPoppy for far-red labeling of proteins. The new fluorogen, tfPoppy, forms a bright far-red assembly with frFAST, a variant of the well-known FAST tag. Emitting at 670 nm with a 115-nm Stokes shift, tfPoppy builds up on FAST legacy: instantaneous, reversible, oxygen-free. frFAST-tfPoppy is hence unique for spectral multiplexing and deep tissue imaging. Moreover, tfPoppy works either with the tag frFAST or its split version, split-frFAST, hence allowing for tracking protein-protein interactions. frFAST is related to the RFP (red fluorescence proteins) family.
The high demand for far-red fluorescent proteins has emerged from the need for new colors. Indeed the growing use of optical biosensors and optogenetic tools obstruct the spectral window available for biological imaging. Moreover, far-red fluorescent proteins allow imaging deeper in tissues. Indeed, autofluorescence, light scattering and absorbance by endogenous molecules is reduced in the far-red region.
Hence the challenge for The Twinkle Factory!
The science behind tfPoppy for far-red labeling
tfPoppy originates from the research led by Prof. Arnaud Gautier. The team gathers researchers from Sorbonne University, Collège de France and ENS of PSL Research University. As a result of their collaboration, they issued an insightful paper in Angew. Chem. Int. Ed. 2020. tfPoppy is therein referred to as HPAR-3OM or (4-hydroxy-3-methoxy-phenyl)allylidene-rhodanine.
The paper discloses a novel far-red system, frFAST and HPAR-3OM, engineered from the original FAST tag and HBR-based fluorogens. Gautier indeed designed HPAR-3OM together with frFAST, specifically for far-red labeling. HPAR-3OM is a membrane-permeant fluorogenic ligand which selectively binds frFAST-tagged proteins. HPAR-3OM is almost non-fluorescent when free in solution. But it strongly fluoresces at 670 nm when bound to frFAST. frFAST and HPAR-3OM allow for imaging proteins in mammalian cells, but also in zebrafish embryo/larvae and chicken embryo. It works in solution, in living cells or in fixed cells. Thereafter Gautier developed a rapid and reversible split-frFAST to image protein-protein interactions in live cells. The paper discloses a variety of application cases.
tfPoppy, a step forward
The Twinkle Factory now sells tfPoppy, the trade name of HPAR-3OM, under the reference 555670-250.
But, as promised earlier, tfPoppy is only the first step towards the color span expansion of our fluorogen range. More to come in 2021. On the other end of the spectrum!
Stain different, tag FAST!