NHS-mPEG

Figure 7.12 Amine-containing dendrimers can be modified using a number of common reactive modification agents. Excess amine groups can be blocked using acetic anhydride, glycidol, or an NHS-mPEG compound. Amines also can be converted into carboxylates using succinic anhydride.

Figure 18.26 The branched PEGylation compound NHS-dPEG fmPEG h contains three mPEG arms, which provide an increased sphere of hydration around modified molecules compared to straight-chain PEGylation compounds.

Figure 25.2 mPEG may be derivatized with succinic anhydride to produce a carboxylate end. A reactive NHS ester can be formed from this derivative by use of a carbodiimide-mediated reaction under nonaqueous conditions. The succinimidyl succinate-mPEG is highly reactive toward amine nucleophiles. 

Figure 25.4 An SC derivative of mPEG was first prepared through the use of phosgene to form a chloroformate intermediate. Reaction with NHS gives the amine-reactive SC-mPEG.

Abuchowski et al. (1984). A method for the succinylation of mPEG can be found in Section 1.3. Subsequent formation of the NHS ester derivatives of these acylated PEG compounds produce a highly reactive polymer that can be used to modify amine-containing molecules under mild conditions and with excellent yields (Figs. 376 and 377). The main deficiency of the succinimidyl succinate or succinimidyl glutarate activation procedures is the potential for hydrolysis of the ester bond formed by acylation of the hydroxyl groups of PEG. 

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