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MPS (NHS-3-maleimidopropionate) (QBD-10217)



MPS (NHS-3-maleimidopropionate), product number QBD-10217, is the N-hydroxysuccinimidyl (NHS) ester of 3-(maleimido)propanoic acid and is used to crosslink sulfhydryls with amines. This product does not contain a dPEG® spacer between the reactive groups. The distance is six atoms (6.0 Å) from the reactive site of the maleimide to the carbonyl carbon of the propanoic acid.

The maleimido group reacts with sulfhydryl groups to form thiol ether bonds. In the range of pH 6.5 – 7.5, the thiol-maleimide reaction is chemoselective. Above pH 7.5, the maleimide group can also react with free amine groups. Consequently, high pH buffers should be avoided when using this product.

NHS esters are widely popular for reactions of carboxylic acids with primary or secondary amines to form stable amide bonds. Although the NHS ester hydrolyzes rather easily in water or aqueous buffer, this product can be dissolved in a water-miscible solvent such as N,N’-dimethylacetamide (DMAC) that has been dried over 3 Å molecular sieves. The solution of MPS is then added to the water or aqueous buffer to start the reaction.


Unit Size250 mg, 1000 mg
Molecular Weight266.21; single compound
Chemical formulaC₁₁H₁₀N₂O₆
Purity> 98%
SpacersSpacer is 6 atoms and 6.0 Å
Typical solubility properties (for additional information contact Customer Support)DMAC or DMSO.
Storage and handling-20°C; Always let come to room temperature before opening; be careful to limit exposure to moisture and restore under an inert atmosphere; stock solutions can be prepared with dry solvent and kept for several days (freeze when not in use). dPEG® pegylation compounds are generally hygroscopic and should be treated as such. This will be less noticeable with liquids, but the solids will become tacky and difficult to manipulate, if care is not taken to minimize air exposure.


  1. Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.
  2. Reagents for Astatination of Biomolecules. 2. Conjugation of Anionic Boron Cage Pendant Groups to a Protein Provides a Method for Direct Labeling that is Stable to in Vivo Deastatination. D. Scott Wilbur, Ming-Kuan Chyan, Donald K. Hamlin, Robert L. Vessella, Timothy J. Wedge, and M. Frederick Hawthorne. Bioconjugate Chem. 2007, 18 (4) pp 1226–1240. June 21, 2007. DOI: 10.1021/bc060345s.
  3. Biodistribution of 211At labeled HER-2 binding affibody molecules in mice. Ann-Charlotts teffen, Ylva Almqvist, Ming-Kuan Chyan, Hans Lundqvist, Vladimir Tolmachev, D. Scott Wilbur and Jorgen Carlsson. Oncology Reports. 2007, 17 (5) pp 1141-1147. May 1, 2007. DOI:

Applicable patents and legal notices are available at legal notices.

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