Table 1.9 Amine-reactive, orange- and red-fluorescent fluorophores.

Fluorophore (Abs/Em) *Succinimidyl EsterOtherProtein Labeling KitsNotes
Lissamine rhodamine B (570/590) L20 (SC)M
L1908 (SC)M
  • Optimal for 568 nm excitation
  • Photostable
Naphthofluorescein (602/672)C653 MC652 (COOH)M 
  • Very long-wavelength excitation and emission
  • pH-sensitive fluorescence, with a high pKa (~7.6)
Rhodamine 6G (525/555)C6127 5
C6128 6
C6157 M
  • Excited by the 514 nm spectral line of the argon-ion laser
  • Spectra intermediate between those of fluorescein and tetramethylrhodamine
Rhodamine Red-X (580/590)R6160 (X)5 F6161 (F)
  • Conjugates of Rhodamine Red-X are generally more fluorescent than those of Lissamine rhodamine B, and the succinimidyl ester is more stable in H2O
Tetramethylrhodamine (555/580)C2211 5
C6123 6
C1171 M
T6105 (X)M
C6121 (COOH)5
C6122 (COOH)6
C300 (COOH)M
T1480 (ITC)5
T1481 (ITC)6
T490 (ITC)M
  • pH-insensitive fluorescence
  • Good photostability
  • Conjugates are prone to aggregation
  • Succinimidyl ester derivative (6-TAMRA, SE; C6123) is widely used for oligonucleotide labeling
Texas Red dye (595/615)T6134 (X)M
T20175 (X)S
T353 (SC)M
T1905 (SC)M
T30200 (DTA)M
F6162 (F)
T10244 (P)
Z25045 (Z)
  • Good spectral separation from green fluorophores
  • Texas Red-X succinimidyl ester typically yields greater fluorescence per attached dye than Texas Red sulfonyl chloride and is more stable in H2O
X-rhodamine (580/605)C6125 5
C6126 6
C1309 M
C6124 (COOH)5
C6156 (COOH)6
X491 (ITC)M
  • Succinimidyl ester derivative (6-ROX, SE; C6126) is widely used for oligonucleotide labeling
* The numbers in parentheses reflect the absorption (Abs) and fluorescence emission (Em) maxima, in nm, of the goat anti–mouse IgG antibody or dextran conjugates in aqueous buffer.

Superscripts 5, 6 and M correspond to 5-isomer, 6-isomer and a mixture of 5- and 6-isomers, respectively.

(COOH) = Carboxylic acid.
(F) = FluoReporter Protein Labeling Kit (Kits for Labeling Proteins and Nucleic Acids—Section 1.2).
(ITC) = Isothiocyanate.
(P) = Easy-to-Use Protein Labeling Kit (Kits for Labeling Proteins and Nucleic Acids—Section 1.2).
(S) = Single isomer.
(SC) = Sulfonyl chloride.
(X) = Aminohexanoyl spacer separating the dye and the SE.
(Z) = Zenon Antibody Labeling Kit (Zenon Technology: Versatile Reagents for Immunolabeling—Section 7.3).