Alexa Fluor dyes

Protein conjugates made with Alexa Fluor dyes produce fluorescence output that surpasses that of other spectrally similar fluorophore-labeled proteins. Alexa Fluor dyes are available in a wide selection of fluorescent colors and are more photostable than most other dyes.

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Unsurpassed Brightness

Alexa Fluor dye molecules can be attached to proteins without significant self-quenching, leading to brighter conjugates. Whether it is Alexa Fluor 488 (Figure 1), Alexa Fluor 555 (Figure 2), or Alexa Fluor 647 (Figure 3), or any other Alexa Fluor dye, you will get the brightest conjugate available for imaging, flow cytometry, and other fluorescence-based applications.

Conjugate Fluorescence

Figure 1.
Comparison of relative fluorescence of goat anti–mouse IgG antibody conjugates prepared from the Alexa Fluor 488 dye and fluorescein isothiocyanate (FITC). Conjugate fluorescence is measured by comparing the fluorescence quantum yield of the conjugated dye relative to that of a reference dye and multiplying by the dye:protein labeling ratio.

Total Fluorescence

Figure 2. Comparison of relative fluorescence of goat anti–rabbit IgG antibody conjugates of the Alexa Fluor 555 and Cy3 dyes at different dye:protein ratios in the conjugate.

Fluorescence Intensity

Figure 3. Flow cytometry comparison of the brightness of Alexa Fluor 647 goat anti–mouse IgG antibody (red, A21235) with Cy5 goat anti–mouse IgG antibody from Jackson ImmunoResearch Laboratories (green) and Amersham-Pharmacia Biotech (blue). Human blood was blocked with normal goat serum and incubated with an anti-CD3 mouse monoclonal antibody; cells were washed, resuspended and incubated with either an Alexa Fluor 647 or Cy5 goat anti–mouse IgG secondary antibody. Samples were analyzed on a flow cytometer equipped with a 633 nm He–Ne laser and a longpass emission filter (>650 nm).

Use Antifade Reagents for Improved Signal Stability

Whether using Alexa Fluor dyes or other standard dyes, you can suppress photobleaching and preserve signal brightness by using Prolong Gold Antifade. Compatible with a multitude of dyes across the spectrum, this is a valuable tool for multicolor applications.

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