5-Carboxytetramethylrhodamine can be used as a fluorescent probe of nucleic acids and proteins. 5-Carboxytetramethylrhodamine displays excitation maxima of 558 nm and an emission maximum of 586 nm[1][2][3].
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[3]. Lyttle MH, et al. A tetramethyl rhodamine (Tamra) phosphoramidite facilitates solid-phase-supported synthesis of 5’-Tamra DNA. J Org Chem. 2000 Dec 29;65(26):9033-8.