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Maleimide-Modifier (5')

picture of Maleimide-Modifier (5')

Modification : Maleimide (5')

Catalog Reference Number
Modification Code
5 Prime
3 Prime
Molecular Weight (mw)
Extinction Coeficient (ec)
Technical Info (pdf)
Absorbance MAX
Emission MAX
Absorbance EC

End Modifiers

Catalog NoScalePrice
26-6574-0550 nmol$105.00
26-6574-02200 nmol$105.00
26-6574-011 umol$136.50
26-6574-032 umol$204.75
26-6574-1010 umol$315.00
26-6574-1515 umol$368.00
Discounts are available for Maleimide (5')!
Modification* Discount Price Structure
1 site/order List price
2 sites/order 10% discount
3 sites/order 20% discount
4 sites/order 30% discount
5-9 sites/order 50% discount
10+ sites/order 60% discount
*Exceptions apply

Maleimide Modifier (5') can be used to directly incorporate an active maleimide moiety onto the 5'-end of an oligonucleotide. The maleimide is separated from the 5'-end nucleotide base by a 2-carbon spacer arm to reduce steric interaction between it and the oligo. Maleimide-labeled oligos are typically used to form conjugates with thiol-labeled moieties, or Diels-Alder cycloaddition products.

As the maleimide moiety itself is not stable over the long-term, Gene Link provides lyophilized maleimido-oligos with all base protecting groups removed and as a maleimide-2,5-dimethylfuran cycloadduct.The cycloadduct serves to protect the maleimide from degradation. The customer then converts the cycloadduct to the active maleimide via a retro-Diels-Alder reaction using toluene and heat. The conversion protocol is provided with the modified oligo. If required the protected oligo should be aliquoted in smaller portions and stored dry.The retro-Diels-Alder reaction should be performed immediately prior to conjugation.

Deprotection by heating in Toluene

Gene Link provides the oligo in a dried lyophilized form. The maleimide is provided in a protected state and deprotection by Retro Diels-Alder reactions is required before use by the end user for conjugation.
The Retro Diels-Alder reactions involves dehydration by co-evaporation with anhydrous acetonitrile and anhydrous toluene. The Retro Diels-Alder reaction requires anhydrous conditions and any significant level of moisture can cause incomplete deprotection, hydrolysis, and/or addition of water to the maleimide. The evaporation of the toluene leaves a white residue ready for conjugation. A detailed procedure is shipped with the product. An abbreviated procedure is described below.
1. Suspend lyophilized oligo in 1 mL anhydrous Acetonitrile. It will be a suspension as oligo will NOT dissolve.
2. Evaporate using a speedvac.
3. Resuspend oligo in 1.5 mL Toulene.
4. Incubate for 4 hrs at 90o C.
5. Cool to room temperature.
6. Evaporate toluene using a speedvac.
7. The oligonucleotide is now ready for conjugation.

Detailed deprotection Retro Diels-Alder reactions protocol Retro Diels-Alder Reaction protocol.

- Maleimide-Modifier (5')

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