5(6)-TAMRA Acid (5(6)-Carboxytetramethylrhodamine, TMR, TRITC) is a bright orange-fluorescent dye with excitation ideally suited to the 532 nm or 546 nm laser lines. It has been used widely for preparing peptide, protein, nucleotide and nucleic acid conjugates, especially fluorescent antibodies and avidin derivatives used in immunochemistry. The absorbance and emission maxima of TAMRA conjugates are 553 nm and 575 nm respectively.
TAMRA Acid is a reagent of choice for the preparation of custom activated esters that often are not commercially available. Examples of such activated esters include sulfo-NHS, TFP (2,3,5,6-Tetrafluorophenol), STP (4-Sulfo-2,3,5,6-Tetrafluorophenol, Sodium Salt). Another common application for non-activated carboxylic acid is peptide modification during solid phase synthesis, which usually requires in-situ activation with peptide coupling regents, for example HATU. TAMRA Acid is also often used for control experiments, and for calibration.