Acid-dPEG®5-NHS ester, product number 10109, is a novel, amine-reactive crosslinker from Quanta BioDesign, Ltd. This product is designed to facilitate intermolecular crosslinking with free amines at each end of the crosslinker through a single molecular weight, discrete polyethylene glycol (dPEG®) backbone. Correct use of this product eliminates intramolecular crosslinking. The dPEG® backbone is amphiphilic. Consequently, it imparts water solubility to molecules to which it is conjugated. There are 19 atoms, including five (5) oxygen atoms, in the dPEG® chain, a distance of 21.6 Å. One end of the chain terminates in a propionic acid group. The other end terminates as the N-hydroxysuccinimidyl (NHS) ester of propionic acid.
Traditional Homobifunctional Crosslinkers
Homobifunctional crosslinkers join two different molecules using the same reactive group. Traditional homobifunctional crosslinkers are hydrophobic. With hydrophobic crosslinkers, aggregation and precipitation of conjugated molecules can be a severe problem. Moreover, all homobifunctional crosslinkers tend to polymerize uncontrollably. Also, when conjugating large biomolecules such as proteins, homobifunctional crosslinkers react both intermolecularly and intramolecularly. Such mixed reactions create a wide variety of products that are difficult to characterize.
The dPEG® difference with Acid-dPEG®5-NHS ester
Quanta BioDesign designed Acid-dPEG®5-NHS ester, product number 10109, to overcome the problems that typically accompany the use of homobifunctional crosslinkers.
Firstly, the amphiphilic dPEG® backbone imparts water solubility to conjugates. Our dPEG® technology creates unique PEG-based products that are soluble in both organic and aqueous media. These products provide all the benefits of traditional PEG products without the attendant difficulties of dispersity. For a thorough explanation of our dPEG® products and technology, please visit our “What is dPEG®?” page. For answers to our most frequently asked questions, please click this link.
Secondly, while both ends of the molecule can react with free amines such as the ε-amine group of lysine, only one end of the dPEG® spacer is activated as the NHS ester. This construction permits only one end of the spacer to react at one time. Thus, users of Acid-dPEG®5-NHS ester react the NHS ester end of the dPEG® molecule with free amines on, for example, a small molecule, peptide, or amine-functionalized surface using appropriate conditions. Then the propionic acid moiety on the opposite end of the molecule is activated with NHS or another suitable acylating agent such as 2,3,5,6-tetrafluorophenol (TFP). (Caution: Users should take care that there are no free amines left on the conjugate molecule that can react with the now-activated end of the dPEG® spacer.) The now-activated conjugate molecule then couples with a different compound or surface containing free amines, forming a unique, intermolecularly conjugated product.
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If you need a homobifunctional crosslinker in your R&D project but dread facing the problems that come from using traditional crosslinkers, click on the “Add to Cart” button now. Start using something that gives you a superior alternative to conventional crosslinkers.