Although the mixed TAMRA isomers are predominantly used for labeling proteins, the single isomers are increasingly preferred for labeling peptides and nucleotides because they give better resolution in HPLC purification that is often required in the conjugation processes. 5-TAMRA is more often used than 6-TAMRA for labeling peptides and proteins. 6-TAMRA is predominately used for labeling nucleotides and sequencing nucleic acids.