This is the comparison of the brightness of the Alexa Fluor 488 and fluorescein conjugates that we publish, which indicates a closer to 1.5 to 2-fold advantage of the Alexa Fluor 488 dye fluorescence intensity over fluorescein on this secondary antibody. A principal advantage of the Alexa Fluor 488 dye over fluorescein is its reduced photobleaching rate and the lack of pH sensitivity of its fluorescence. Figure 1.12 Comparison of the relative fluorescence of goat anti–mouse IgG conjugates prepared from the Alexa Fluor 488 dye and from fluorescein isothiocyanate (FITC). Conjugate fluorescence is determined by measuring the fluorescein quantum yield of the conjugated dye relative to that of a reference dye and multiplying by the dye:protein labeling ratio. [Image] John Krowka wrote: > On Molecular Probes' website are claims that Alexa 488 is 6-7 times brighter > than FITC. Preliminary evidence from our conjugations of the same antibody > with FITC or Alexa 488 indicate no advantage from using Alexa 488. Can > anyone who compared Alexa 488 and FITC share their findings?
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