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Fluorescein Maleimide (SP-1502-12)

The product has been discontinued

Please contact Technical Support @ [email protected] for assistance in finding alternative.

The product has been discontinued

We have discontinued this product permanently. Please find alternative products from below section:

Goat Anti-Fluorescein, Biotinylated (BA-0601-.5)

3′ EndTag™ DNA End Labeling System (MB-9002)

Biotin (Long Arm) Maleimide (SP-1501-12)


Fluorescein Maleimide is used to label free thiol groups with fluorescein.  This fluorescent label can be directly visualized or used as a specific tag that can be detected with anti-fluroescein antibodies. For labeling nucleic acids, thiols can be introduced into DNA, RNA, or oligonucleotides using the 5′ EndTag™ or 3′ EndTag™ nucleic acid labeling systems.


Unit Size12 mg
Target for LabelingDNA, Oligonucleotides, PNA, Protein, RNA
Recommended Storage– 20°C to – 80 °C.
Molecular Weight498.4
Chemical FormulaC27H18N2O8
Maximum Emission520 nm
Maximum Excitation492 nm
Required Reactive GroupThiol Group
Tag/Group IncorporatedFluorescein
Safety TitleWARNING: NA –


Technical Information

Fluorescein Maleimide is designed for fluoresceinating proteins, nucleic acids or other molecules containing one or more thiol groups. Molecules to be labeled with Fluorescein Maleimide require free thiol groups. In the case of proteins, Fluorescein Maleimide will react with exposed cysteine residues. Alternatively, free thiols may be generated by reducing disulfide bonds or by modifying other reactive groups such as primary amines with compounds like Traut’s reagent (2-iminothiolane).

This fluorescent label can be directly detected or used as a hapten and detected with our high affinity antibody reagents. (Excitation maximum at 495 nm; emission maximum at 515 nm).

Applicable patents and legal notices are available at legal notices.