Fluorescein and Derivatives

Fluorescein fluorophores have been the most common fluorescent derivatization reagents for covalently labeling proteins. Fluorescein isothiocyanates (FITC) are the predominantly used fluorescein derivatives. But alternative derivatives offer significant advantages. Carboxyfluorescein succinimidyl esters react faster than FITC and yield conjugates with higher resistance against hydrolysis. An advantage of fluorescein dichlorotriazine (DTAF) is its direct reactivity with polysaccharides and other alcohols in aqueous solutions at pH greater than nine. 6-carboxy-4′,5′-dichloro-2′,7′-dimethoxyfluorescein (JOE) is very common as label for automated nucleic acid sequencing. The synthesis of these derivatives typically results in a mixture of isomers, which are almost indistinguishable in both wavelength and intensity, but may differ in the geometry of their binding to proteins. Certain applications may require the single-isomer preparations.

Product #

Description

Assay

Fluorescence

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35845 2′,7′-Dichlorofluorescein diacetate ≥95% (HPLC)
λex 504 nm; λem 524 nm in 0.1 M Tris pH 8.0 (esterase)
C7153 5(6)-Carboxyfluorescein Mixed isomers ~99% (HPLC)
 
C8166 5(6)-Carboxyfluorescein diacetate Mixed isomers ≥90% (HPLC)
 
21888 5(6)-Carboxyfluorescein diacetate N-succinimidyl ester ≥90% (HPLC)
λex 492 nm; λem 517 nm in 0.1 M Tris pH 8.0 (esterase)
72755 5-(Bromomethyl)fluorescein ≥95% (sum of tautomers, GC)
λex 492 nm; λem 515 nm in 0.1 M Tris pH 9.0
I9271 5-(Iodoacetamido)fluorescein ≥90% (HPLC)
λex 492 nm; λem 515 nm (Mercaptoethanol adduct)
λex 493 nm; λem 522 nm (pH 9.2)
D0531 5-([4,6-Dichlorotriazin-2-yl]amino)fluorescein hydrochloride ≥90% (HPLC)
λex 495 nm; λem 516 nm
87444 5-Carboxy-fluorescein diacetate N-succinimidyl ester ≥95.0% (HPLC)
λex 492 nm; λem 517 nm
86826 5-Carboxyfluorescein ≥95% (HPLC)
λex 492 nm; λem 517 nm in 0.1 M Tris pH 8.0
92846 5-Carboxyfluorescein N-succinimidyl ester ≥90% (HPLC)
λex 492 nm; λem 520 nm in 0.1 M Tris pH 8.0
08951 6-Carboxy-fluorescein diacetate N-succinimidyl ester ≥90.0% (HPLC)
λex 492 nm; λem 517 nm in 0.1 M Tris pH 8.0 (after cleavage by esterase)
46935 6-[Fluorescein-5(6)-carboxamido]hexanoic acid ≥90% (HPCE)
λex 491 nm; λem 515 nm in 0.1 M Tris pH 9.0
46940 6-[Fluorescein-5(6)-carboxamido]hexanoic acid N-hydroxysuccinimide ester ≥75% (HPLC)
λex 490 nm; λem 514 nm (pH 8.2)
λex 491 nm; λem 515 nm in 0.1 M Tris pH 9.0
C4109 6-Carboxy-4′,5′-dichloro-2′,7′-dimethoxyfluorescein N-hydroxysuccinimide ester    
C0662 6-Carboxyfluorescein ~97% (HPLC)
λex 492 nm; λem 517 nm (pH 8.0)
E6003 Eosin Y disodium salt    
E4382 Eosin Y disodium salt    
45240 Eosin Y disodium salt   λem 540 nm in H2O
λex 532 nm
318906 Eosin Y solution    
F2456 Fluorescein (free acid)    
F3651 Fluorescein 5(6)-isothiocyanate ≥90% (HPLC)
 
46950 Fluorescein 5(6)-isothiocyanate ≥90% (HPLC)
λex 492 nm; λem 518 nm in 0.1 M phosphate pH 8.0
16231 Fluorescein diacetate 5(6)-isothiocyanate ≥90% (sum of iosmers, HPLC)
λex 497 nm; λem 517 nm in 0.1 M phosphate pH 7.0 (esterase)
46939 Fluorescein diacetate 5-maleimide   λex 492 nm; λem 530 nm in 0.1 M phosphate pH 7.0 (after derivatization with 2-mercaptoethanol and after cleavage by esterase)
36438 Fluorescein diacetate 6-isothiocyanate ≥90% (HPLC)
λex 496 nm; λem 517 nm in 0.1 M Tris pH 8.0, esterase
F7250 Fluorescein isothiocyanate isomer I ≥90% (HPLC)
λex 492 nm; λem 518 nm (green)
F4274 Fluorescein isothiocyanate isomer I ≥97.5% (HPLC)
λex 492 nm; λem 518 nm (green)
46951 Fluorescein isothiocyanate isomer I ≥97.5% (HPLC)
λex 492 nm; λem 518 nm (green)
λex 492 nm; λem 518 nm in 0.1 M phosphate pH 8.0
46970 Fluorescein sodium salt   λex 460 nm; λem 515 nm(lit.)
F9551 Fluorescein-5-EX N-hydroxysuccinimide ester    
88596 Fluorescein-O′-acetic acid ≥90% (HPCE)
λex 455 nm; λem 514 nm in 0.1 M Tris pH 8.0
07294 O′-(Carboxymethyl)fluoresceinamide ≥97.0% (HPCE)
λex 458 nm; λem 520 nm in methanol