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MAL-dPEG®₄-Glu(TFP ester)-NH-m-dPEG®₂₄ (QBD-11581)



MAL-dPEG®4-Glu(TFP)-NH-m-dPEG®24, product number QBD-11581, is one of Vector Laboratories’ unique, patented class of modular, designable payload delivery reagents called Sidewinder™. Sidewinder™ products are built on a discrete PEG (dPEG®) backbone for use in antibody-drug conjugates (ADCs) and related constructs. The payload (cytotoxin, dye, small molecule) loads onto the chain’s sidearm. The distal end’s methoxy-terminated dPEG®24 spacer protects payloads and modifies performance.

The maleimide reactive group of MAL-dPEG®4-Glu(TFP)-NH-m-dPEG®24, product number QBD-11581, reacts with free thiols on the biomolecule through the thiol-maleimide reaction (a Michael addition reaction) to form a stable thioether bond. The sidearm is functionalized as the 2,3,5,6-tetrafluorophenyl ester (TFP ester) and reacts with free amines to form stable amide bonds. TFP esters have an optimal reaction pH range of 7.5 – 8.0. They are more hydrolytically stable than NHS esters and more reactive toward amines than NHS esters in the optimal pH range.

Sidewinder™ products are designed to facilitate the creation of stable, high-DAR ADCs. Published research has shown that putting a hydrophobic payload close to the antibody surface and protecting it with a SuperHydrophilic™ dPEG® construct is better by many measures of efficacy than putting the payload at the distal end of the linker. This molecule can also modify and optimize BD, cell trafficking and internalization, serum half-life, and immunogenicity.

The dPEG® linkers and spacers in the Sidewinder™ construct are uniform, single molecular-weight PEGs with discrete chain lengths. In contrast, traditional, non-uniform polymer PEG linkers and spacers have a dispersed range of PEG chain lengths, each with a unique molecular weight. Unlike dispersed polymer PEGs, dPEG® products are high-purity compounds with reproducible purity profiles.

Sidewinder™ molecules are also fully designable. MAL-dPEG®4-Glu(TFP)-NH-m-dPEG®24 can be modified to change the spacer lengths, add more sidearm attachment points, add different sidearm attachment points to carry payloads with other reactivities, change the maleimide attachment group to another reactive group, and many more customizations. Please inquire about your specific needs.


Unit Size50 mg, 250 mg
Molecular Weight1763.90; single compound
Chemical formulaC₇₈H₁₃₄F₄N₄O₃₅
Purity> 95%
SpacersdPEG® Spacer is 99 atoms and 104.9 Å
Typical solubility properties (for additional information contact Customer Support)Methylene Chloride, Methanol or Acetonitrile.
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.


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.

Applicable patents and legal notices are available at legal notices.

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