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Thermo Scientific™ Pierce™ Methyl-PEG-Maleimide Reagents

Pegylate sulfhydryls (-SH groups) on proteins (cysteine residues) or assay surfaces using MS(PEG); sulfhydryl-reactive (maleimide), PEG compounds (12 and 24 EG units).

Manufacturer:  Thermo Scientific™ 22713

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Catalog No. PI22713



Thermo Scientific™ Pierce MM(PEG)12 is a methyl-terminated, polyethylene glycol compound (3 times 12 PEG units) activated with a maleimide group for covalent pegylation of sulfhydryls on proteins (e.g., cysteines) or assay surfaces.

MM(PEG)n is the abbreviation for a set of compounds having polyethylene glycol (PEG) spacers with methyl (—CH3) and sulfhydryl-reactive maleimide groups at opposite ends. The unbranched, hydrophilic, discrete-length molecules have the form Methyl-PEGn-Maleimide, where the subscript “n” denotes 12 or 24 ethylene glycol units. The maleimide is spontaneously reactive with sulfhydryl (—SH) groups, providing for efficient PEGylation of proteins, peptides and other cysteine- or thiol-containing molecules.


  • Maleimide-activated for efficient PEGylation of sulfhydryl groups at pH 6.5-7.5; reaction of maleimide group results in formation of stable, irreversible thioether bonds
  • Fully characterized PEGylation reagents with defined PEG chain lengths; molecules of discrete molecular weight for consistency of performance in protein-modification applications
  • Provided with either 12 or 24 ethylene glycol units, enabling modification procedures to be optimized for a specific application while retaining all the benefits associated with protein PEGylation
  • PEG spacer provides unique advantages, including increased stability, reduced tendency toward aggregation and reduced immunogenicity
  • Easy-to-follow instructions increase the likelihood of a successful outcome


24-unit ethyleneglycol functionalized with methyl and maleimido ends; solid
81mL of typical 1X (1mM) reaction solution, or approx. 50 uses at 2mg reagent per use
Pierce MM(PEG)24