Amino-dPEG®₈-t-butyl ester

Amino-dPEG®8-t-butyl ester, product number 10271, is a carbonyl- and amine-reactive, single molecular weight polyethylene glycol (PEG) crosslinker with a discrete chain length. The compound consists of a primary amine and a propionic acid tert-butyl ester on opposite ends of a discrete PEG (dPEG®) spacer. The amine end of the molecule reacts readily with carbonyl groups (aldehydes, ketones, and carboxylic acids). A cleavable tert-butyl ester group protects the propionic acid end of the product. The ester cleaves with trifluoroacetic acid (TFA), leaving the propionic acid moiety free to react with amines either by activation with an acylation reagent or by direct coupling to an amine using a carbodiimide.

Heterobifunctional Crosslinkers
Heterobifunctional crosslinkers join different reactive functional groups together through a crossbridge. Crosslinkers that join amines and carboxylates are particularly popular. However, conventional crosslinkers are often hydrophobic and may trigger aggregation and precipitation of conjugates that use them.

In contrast, our dPEG® crosslinkers are highly water-soluble amphiphiles. Consequently, dPEG® crosslinkers impart water solubility to conjugates that incorporate them. As a result, these crosslinkers are increasingly popular in bioconjugation applications. Moreover, our dPEG® products provide all of the benefits of traditional PEG products without the analytical headaches that inevitably arise from using disperse polymer products.

Using Amino-dPEG®8-t-butyl ester
The amine end of the molecule reacts with activated carboxylic acid esters (for example, N-hydroxysuccinimidyl or tetrafluorophenyl esters) to form an amide bond. Also, carboxylic acids can couple to the amine end of Amino-dPEG®8-t-butyl ester using a carbodiimide such as EDC, with or without an acylating agent such as HOBt.

After working up the reaction to remove unreacted components and isolate the intermediate, trifluoroacetic acid is used to remove the tert-butyl ester and expose the propionic acid end group. The exposed carboxylic acid can then react further. For example, activation as the NHS or TFP ester is possible. Also, the acid can be coupled directly to an amine as described above.

Literature References to Amino-dPEG®8-t-butyl ester
Amino-dPEG®8-t-butyl ester, product number 10271, is highly cited in scientific literature and patents. The range of applications successfully demonstrating the use of Amino-dPEG®8-t-butyl ester is quite broad.

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