Texas Red-X, ortho succinimidyl ester *Single isomer*

The amine-reactive Texas Red(R)-X, succinimidyl ester is a superior replacement to Texas Red (Texas Red(R) is the trademark of ThermoFisher). Most commercial vendors only offer the mixed isomers of para and ortho positions. AAT Bioquest is the only vendor that offers the single isomer of both para (#474) and ortho isomer (#476), and their mixed isomers (#475). The para (#474) and ortho isomer (#476) have almost the same spectral properties to Texas Red. They can be used to create bright red-fluorescent bioconjugates with excitation/emission maxima ~595/615 nm. Compared to Texas Red(R), Texas Red(R)-X dye contains an additional seven-atom aminohexanoyl spacer ("X") between the fluorophore and the succinimidyl ester group. This spacer helps to separate the fluorophore from its point of attachment, potentially reducing the interaction of the fluorophore with the biomolecule to which it is conjugated. Compared to the mixed isomers (#474), this product is the single 2-isomer, giving more reproducible results.