Thermo Scientific™


Catalog number:  62245

 Related applications:

Protein Labeling & Crosslinking

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Thermo Scientific Fluorescein-5-Maleimide is a high-performance derivative of fluorescein dye, activated for easy and reliable labeling of antibodies, proteins and other molecules for use as fluorescent probes. Fluorescein-5-Maleimide is a sulfhydryl-reactive derivative of fluorescein that labels proteins and other molecules having free thiols (cysteine side chains)

Properties of Fluorescein-5-Maleimide:

• Alternative names: 5-MF, 5-maleimido-fluorescein
• Chemical name: 1H-Pyrrole-2,5-dione, 1-(3',6'-dihydroxy-3-oxospiro (isobenzofuran-1(3H),9'-(9H)xanthen-5-yl)-
• Molecular weight: 427.36±3
• Excitation source: 488 nm spectral line, argon-ion laser
• Excitation wavelength: 494 nm
• Emission wavelength: 518 nm
• Extinction coefficient: > 80,000 M-1cm-1
• CAS #: 75350-46-8
• Solubility: Soluble in DMF or DMSO
• Reactive groups: Maleimide, reacts with sulfhydryls at pH 6.5 to 7.5

• Label antibodies for use as immunofluorescent probes
• Label oligonucleotides for hybridization probes
• Detect proteins in gels and on Western blots

Related Products
5-IAF (5-iodoacetamido-fluorescein)
For Research Use Only. Not for use in diagnostic procedures.


Chemical Reactivity: Thiol
Excitation⁄Emission (nm): 494⁄518
Label or Dye: FITC (Fluorescein), Fluorescein (FITC)
Product Line: Pierce™
Product Size: 25 mg
Solubility: DMF (Dimethylformamide)

Contents & storage

Store desiccated at -20°C, protect from moisture


Manuals & protocols