MAL-dPEG®₁₂-Tris(-dPEG®₁₁-amido-MAL)₃

MAL-dPEG®12-Tris(-dPEG®11-amido-MAL)3, product number QBD-11433, is a branched, single molecular weight, thiol-reactive, discrete polyethylene glycol (dPEG®) product. It is designed to join up to four molecules via a maleimide-thiol reaction. Built around a tris core and terminated on each arm with a thiol-reactive maleimide group, this homotetrafunctional crosslinker is 96 atoms long (124.4 Å) from one maleimide to another.

The thiol-maleimide reaction, also known as the thiol-Michael addition, is a click chemistry reaction. This powerful, highly popular reaction is extensively used in bioconjugation applications. At pH 6.5 – 7.5, the thiol-maleimide reaction is chemoselective. However, above pH 7.5, the maleimide group reacts competitively with amines, so the pH should be kept below this limit.

Unlike traditional polyethylene glycol (PEG), which are non-uniform, dispersed polymers, Vector Laboratories’ dPEG® products are single molecular weight PEGs with discrete chain lengths, hence the dPEG® name. The four arms of MAL-dPEG®12-Tris(-dPEG®11-amido-MAL)3 are built around a core of tris(hydroxymethyl)aminomethane (“”tris””). Although one arm is differently structured than the other three arms (one dPEG®12 arm vs. three dPEG®11 arms), each arm has the same number of atoms and the same length when measured from the reactive site on the maleimide to the tris core from which each arm branches. This precise construction occurs because the dPEG® spacers have discrete chain lengths. This product can link multiple peptides or proteins together for drug delivery. It could also be used as a core unit for constructing dendrimers with precisely defined spacer lengths.