Common DNA labeling reagent, also used for protein labeling.
Carboxytetramethylrhodamine (TAMRA) is a fluorescent dye that is a derivative of rhodamine. This methyl derivative emits in the red region of the spectrum and is often used to label oligonucleotides at the 5'- or 3'-ends, or internally. TAMRA has an absorbance maximum of 565 nm and an emission maximum of 580 nm. TAMRA-modified oligonucleotides play a particularly important role in both fluorescence resonance energy transfer (FRET) and real-time PCR applications.
FRET is a distance-dependent interaction between two dye molecules in which excitation is radiationlessly transferred from one dye (the donor) to the second dye (the acceptor), due to their spectral overlap. Because the efficiency of the energy transfer is extremely sensitive to the distance between the molecules (varying as the inverse sixth power of that distance), FRET can be used to study biological proximity.. For oligonucleotides slated for use in FRET application, a common donor-acceptor pair is 6-aminofluorescein (6-FAM) (as donor) / TAMRA (as acceptor), due to their good spectral overlap. When 6-FAM is excited at 492 nm and transfers this energy to TAMRA, which then emits light at 580 nm. FRET oligo probes are widely used to monitor biochemical reactions, particularly inin vivo studies.
Besides being used as a FRET fluorophore, TAMRA also can be used as a FRET-based quencher moiety in real-time PCR probes such as TaqMan probes, Scorpion primers and Molecular Beacons.
TAMRA also can be used to label DNA oligos for use as hybridization probes in a variety of in vivo and in vitro research or diagnostic applications, as well as for structure-function studies of DNA, RNA, and protein-oligonucleotide complexes. Oligos labeled with TAMRA at the 5'-end can be used as PCR and DNA sequencing primers to generate fluorescently-labeled PCR, sequencing or genetic analysis (AFLP or microsatellite) products.
TAMRA is often employed in the form of an NHS ester (see our Product M0972) where the oligo must contain an Amino C6 Linker (for the ends) or the Amino C6 version of the base phosphoramidite (for internal labeling). The TAMRA-NHS ester is then manually attached to the oligo through the amino group in a separate reaction post-synthesis. TAMRA is also used for protein labeling where it can be added to the amino terminus or to lysine residues.
Room Temperature, Protect From Light
References and Citations
Du Y.(2015) "Fluorescence polarization assay to quantify proteinprotein interactions in an HTS format." Methods in Molecular Biology (New York, NY, United States) Protein-Protein Interactions (1278) 529-544.
Srinivasan D, Muthukrishnan N, Johnson GA, Erazo-Oliveras A, Lim J, Simanek EE, Pellois J-P (2011) "Conjugation to the cell-penetrating peptide TAT potentiates the photodynamic effect of carboxytetramethylrhodamine." PLoS One 6(3), e17732.
Mayr T, Moser C, Klimant I. (2007) "Luminescence decay time encoding of magnetic micro spheres for multiplexed analysis." Analytica Chimica Acta 597(1) 137-144.
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