5-ROX, SE [5-Carboxy-X-rhodamine, succinimidyl ester] *CAS 209734-74-7*

Single isomers of ROX are increasingly preferred for labeling peptides and nucleotides because they give 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. 5-ROX is predominantly used to label peptides and proteins. Compared to other rhodamines, ROX is very unstable. Cautions must be exercised to prevent the deterioration during storage.