6-ROX N-succinimidyl ester

6-ROX N-succinimidyl ester (6-ROX-SE) is an amine-reactive long wavelength rhodamine dye. Derivatives made with the amine-reactive carboxy-X-rhodamine (ROX), succinimidyl ester are widely used for oligonucleotide labeling and automated DNA sequencing applications. Conjugates of this dye have longer-wavelength spectra than the spectra of Lissamine rhodamine B conjugates, but somewhat shorter-wavelength spectra than those of Texas Red conjugates. 6-ROX-SE derivatized compounds such as proteins, nucleic acids and drugs may be analyzed by fluorescence resonance energy transfer (FRET) and fluorescence quenching applications. 6-ROX-SE is a labeling reagent for preparation of charge-modified dye-labeled ddNTPs to "direct-load" DNA sequencing. 6-ROX-SE is a single isomer of ROX and increasingly preferred for labeling peptides and nucleotides because it gives better resolution in HPLC purifications that are often required in bioconjugations. Variable ratios of the 5- and 6-isomers often cause complications in the interpretation of labeling results and assay performances. Spectral data: λex=578nm; λem=604nm; Extinction coefficient (cm-1M-1): 82000; Quantum yield: 0.94 (aqueous buffer pH 7.0).