Succinimidyl succinate

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. 

Unlike the succinimidyl succinate or succinimidyl glutarate activation methods, SC chemistry does not suffer from the presence of a labile ester bond. The intermediate reactive NHS carbonate may hydrolyze in aqueous solution to release NHS and CO2, essentially regenerating... 

Figure. 25.3 Succinimidyl succinate-mPEG may be used to modify amine-containing molecules to form amide bond derivatives. The ester bond of the succinylated mPEG, however, is subject to hydrolysis.

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. 

Unlike the succinimidyl succinate or succinimidyl glutarate activation methods, succinimidyl carbonate chemistry does not suffer from the presence of a labile ester bond. The intermediate carbonate may hydrolyze in aqueous solution to release NHS and C02, essentially regenerating the underivatized PEG hydroxyl. After coupling to amine-containing molecules, however, the resultant carbamate linkage stabilizes the chemistry to the point that a modified molecule will not lose PEG by hydrolytic cleavage. For these reasons, the succinimidyl carbonate method of PEG activation and... 

Ethylenglycol-bis-(succinimidyl- succinate) Lys residues Chemical reaction at pH 8, cross-linked proteins are deavable with hydroxylamine... 

Monomethoxy polyethylene glycol succinimidyl succinate (PEG-OSu), mol wt approx 5000, octyl glucoside (OG), cholesterol, stearyl amine (S A), and buffers, such as HEPES and MES, are available from Sigma (St. Louis, MO). 

In the case of mPEG N-succinimidyl succinate, the reaction also leads to a stable amide linkage to protein amino groups, but the linker to PEG bears an ester group which is hydrolyzed in vivo by esterases [16]. 

Figure 4.5-1. Chemical structures of activated PEGs for amine conjugation (a) PEG-dichlorotriazine (b) PEG-tresylate (c) PEG-aldehydes (d) PEG-succinimidyl succinate (e) PEG-imidazole carbonate (f) PEG-phenyl carbonate (g) PEG-succinimidyl carbonate (h) PEG-benzotriazole carbonate and (i) PEG-active ester.

PEG-succinimidyl carbonate (Figure 4.5-lg) is another activated PEG that specifically reacts with amino groups of proteins, thus forming a carbamate linkage [28]. It is found to be more selective than PEG-succinimidyl succinate for modification of the amino groups of proteins. In particular, PEG-succinimidyl carbonate is... 

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