The amine-reactive BODIPY® TR-X succinimidyl ester can be used to create red-fluorescent bioconjugates. This reactive 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. The electronically neutral BODIPY® TR dye is spectrally similar to the red fluorescent Texas Red® dye.