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Trace Fluorescent Labeling Crystallization

Proteins naturally exhibit weak fluorescence due to aromatic amino acid residues such as trptophan. The fluorescent properties can be greatly enhanced by labeling the protein with a covalently bound fluorescent probes. Taking advantage of this, monitoring the crystallization process becomes easier and faster by checking the intensity of fluorescence in the crystallization plates, instead of observing the shape of crystals.

Trace fluorescent labeling (TFL) is one of the most advanced fluorescence method for the detection and identification of macromolecular crystals. The target protein is covalently labeled (usually on the side-chain amine) with a visible-wavelength fluorescent probe. The probe typically labels ≤0.20% of the protein molecules and is concentrated along with the formation of crystals, producing fluorescence that is easily detected by visual examination. Salt crystals do not fluoresce at all, and the fluorescence emitted from amorphous precipitate is weak, so the hidden leads in amorphous precipitate can also be easily detected.

Visualization of  crystals using TFL  method. Figure 1. Visualization of crystals using TFL method.

Our trace fluorescent labeling system has many advantages: 1) The entire protein-labeling workflow can be finished within 20 min with relatively low cost; 2) the final probe concentration is low enough to have little adverse effect on the crystal nucleation or diffraction quality; 3) the wavelength is selectable so that potential interfering substance can be avoided; 4) researchers can view the screening results directly through the microscopy without camera for imaging.

Creative Biostructure now provides custom trace fluorescent labeling service as a powerful tool for the identification of macromolecular crystals. With our UniCrys™ high-throughput crystallization platform, we guarantee to offer this service with high efficiency at a competitive low price to aid your crystallization screening experiment.

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  1. Pusey M, et al. (2015) Trace fluorescent labeling for protein crystallization. Acta Crystallogr F Struct Biol Commun 71(Pt 7):806-814.
  2. Forsythe E, et al. (2006) Trace fluorescent labeling for high-throughput crystallography. Acta Crystallogr D Biol Crystallogr 62(Pt 3):339-346.

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