MPEG-maleimide

Several PEG reagents are available for site-specific PEGylation with protein cysteine thiols. mPEG-maleimide reacts to form a stable sulfide linkage via a 1,4-addition reaction of the thiol to the a,) -unsaturated site on the maleimide moiety [24]. 

More recently it has been claimed that mPEG-amine 42 can react with N-methoxycarbonylmaleimide in aqueous basic solution, rendering the required mPEG maleimide 37 in a single step [180]. 

Poly(ethylenglycol)-a-distearoyl phosphatidylethanolamine,-w-maleimide FW 3,400 (mPEG-DSPE-maleimide, from Shearwater Polymers, Huntsville, AL). Dissolve mPEG-DSPE-maleimide in DMSO at 10 mg/mL immediately before reaction. 

To make scVEGF-lipid conjugate, add mPEG-DSPE-maleimide directly to deprotection reaction to a final molar protein-to-lipidratio of 1 2. Residual DTT will not affect modification reaction. Incubate lipidation reaction mixture at room temperature for 1 h. 

Weigh 2-4 mg of mPEG-DSPE-maleimide, and dissolve it in DMSO to make a final concentration of 10 mg/mL (2.9 mM). Add mPEG-DSPE-maleimide directly to Trout s reaction for a final protein-to-lipid molar ratio of 1 2. Incubate the reaction at room temperatnre for 1 h. 

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