MAL-dPEG®₃₆-NHS ester

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PRODUCT IS SOLD STRICTLY FOR INTERNAL LABORATORY AND RESEARCH PURPOSES ONLY AND HAS NOT BEEN REVIEWED BY THE FDA. PRODUCT IS NOT FOR RESALE AND CANNOT BE INCORPORATED INTO COMMERCIAL GOODS FOR ANY USE OR USED IN THE DEVELOPMENT OF COMMERCIAL PRODUCTS OR IN THE PERFORMANCE OF COMMERCIAL SERVICES UNLESS UNDER A SEPARATE LICENSING, SUPPLY, OR DISTRIBUTOR AGREEMENT WITH QUANTA BIODESIGN, LTD. For information pertaining to the commercial use of our products, please click here to contact us.

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MAL-dPEG®36-NHS ester, product number 10904, crosslinks sulfhydryl groups to free amines. Free thiols react with maleimide groups via a Michael addition reaction. At the same time, amines form amide bonds with the crosslinker by nucleophilic substitution of the N-hydroxysuccinimidyl (NHS) ester of a carboxylic acid group. The maleimide and NHS functional groups on the crosslinking compound sit at either end of a long, flexible, discrete-length polyethylene glycol chain (dPEG®).

The most popular[1], most useful[2] crosslinking reactions in bioconjugate chemistry are those that join free thiols to free amines using heterobifunctional reagents that bridge the two groups. Traditional crosslinkers are hydrophobic molecules, and the conjugation of conventional hydrophobic crosslinking reagents to biomolecules almost inevitably triggers problems such as aggregation and precipitation of the conjugates. By contrast, Quanta BioDesign’s dPEG® crosslinking products are water-soluble, amphiphilic, single molecular weight PEG compounds with discrete chain lengths. Because of our dPEG® products’ hydrophilicity, these problems do not occur when using our crosslinkers on biomolecules. For more information about our dPEG® products, please see our “What is dPEG®?” page. Also, click here for answers to our most frequently asked questions.

How to Use MAL-dPEG®36-NHS ester

As NHS esters hydrolyze readily in water or aqueous buffer, the NHS ester end of the molecule must conjugate to a target molecule before conjugating the maleimide end of the molecule. NHS esters react optimally with free amines at pH 7.0 – 7.5, but they can react with free amines as low as pH 6.0. Moreover, the NHS ester’s hydrolysis rate increases as the pH increases. Indeed, at pH 7 and 0°C, the NHS ester’s half-life is four (4) to five (5) hours in aqueous buffer, while at pH 8 and 25°C, the half-life of an NHS ester is one hour.[3] Thus, we strongly discourage storing MAL-dPEG®36-NHS ester, product number 10904, in water or aqueous buffer. Instead, we recommend that customers make new solutions of the product as needed, use them immediately, and discard unused solutions after use. Please note that our product’s carboxylic acid group is a propionate moiety rather than an acetate group for stability reasons.[4]

The reaction of the maleimide end of MAL-dPEG®36-NHS ester, product number 10904, with a sulfhydryl proceeds best at pH 6.5 – 7.5. Conduct the conjugation at the lowest reasonable pH within this range. Above pH 7.5, free amines compete with free thiols at the maleimide reaction site, which may lead to undesirable crosslinking and confusing results. Moreover, the maleimide ring may open at higher pH values to form unreactive maleamic acid.[5] For details about maleimide-thiol reaction chemistry, please click here.

Uses of MAL-dPEG®36-NHS ester

The use of MAL-dPEG®36-NHS ester, product number 10904, has been published in several scientific papers and patents. One of the most notable uses of this product is in the development of extracellular drug conjugates (EDCs), a type of antibody-drug conjugate (ADC) for targeting extracellular markers.[6],[7] Other potential uses for this compound include the following:

  • targeted delivery of cancer drugs via ADCs;
  • as a long, flexible tether between atomic force microscopy probes and molecules of interest (g., antibodies); and,
  • surface coating of nanoparticles.

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Please click the “Add to Cart” button now to order MAL-dPEG®36-NHS ester, product number 10904.

References

[1] Hermanson, G. T. Chapter 6, Heterobifunctional Crosslinkers. In Bioconjugate Techniques, 3rd ed.; Academic Press: New York, NY, 2013; pp 299–340, specifically page 300. Many scientists engaged in bioconjugation work consider Greg Hermanson’s book to be the definitive reference on the subject. Click here now to read a review of Greg’s book and to purchase it.

[2] Hermanson, G. T. Chapter 18, PEGylation and Synthetic Polymer Modification. In Bioconjugate Techniques, 3rd ed.; Academic Press: New York, NY, 2013; pp 787–838, specifically page 794.

[3] Hermanson, G. T. Chapter 3, The Reactions of Bioconjugation. In Bioconjugate Techniques; Academic Press: New York, NY, 2013; pp 229–258, specifically page 234.

[4] Harris, J. M.; Kozlowski, A. Poly(Ethylene Glycol) and Related Polymers Monosubstituted with Propionic or Butanoic Acids and Functional Derivatives Thereof for Biotechnical Applications. US5672662A, September 30, 1997. See Table 1.

[5] Hermanson, G. T. Chapter 6, op. cit., page 304.

[6] Marshall, D. J.; Harried, S. S.; Murphy, J. L.; Hall, C. A.; Shekhani, M. S.; Pain, C.; Lyons, C. A.; Chillemi, A.; Malavasi, F.; Pearce, H. L.; Thorson, J. S.; Prudent, J. R. Extracellular Antibody Drug Conjugates Exploiting the Proximity of Two Proteins. Molecular Therapy 2016, 24 (10), 1760–1770. https://doi.org/10.1038/mt.2016.119.

[7] Prudent, J. R. Extracellular Targeted Drug Conjugates. 20200384122, December 10, 2020.

Additional information

Weight.5 oz
Dimensions.75 × .75 × 2 in
Size

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