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Thermo Scientific™ Pierce™ Methyl-PEG-NHS-Ester Reagents

Pegylate amines (-NH2 groups) on proteins (lysine residues) or assay surfaces using MS(PEG)n, amine-reactive (NHS ester), methyl-capped PEG compounds (4 to 24 EG units).

Manufacturer: thermo scientific™  22341

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Catalog No. PI22341


Description & Specifications


Capping Group Methyl
Chemical Reactivity Amine
Cleavable No
Description Pierce MS(PEG)4
Formulation 4-unit ethyleneglycol functionalized with methyl and succinimidyl ends; pale liquid
Molecular Weight 333.33
PEGylated Yes
Quantity 100mg
Sufficient For 300mL of typical 1X (1mM) reaction solution, or approx. 50 uses at 2mg reagent per use
Spacer Arm Length 16.4Å
Storage Requirements -20°C

Thermo Scientific™ Pierce MS(PEG)n reagents are methyl-terminated, polyethylene glycol compounds (n equals 4 to 24 PEG units) activated as NHS esters for covalent pegylation of primary amines on proteins (e.g., lysines) or assay surfaces.

MS(PEG)n is the abbreviation for a set of compounds having polyethylene glycol (PEG) spacers with methyl (—CH3) and amine-reactive NHS-ester groups at opposite ends. The unbranched, hydrophilic, discrete-length molecules have the form Methyl-PEGn-NHS Ester, where the subscript “n” denotes 4, 8, 12, or 24 ethylene glycol units. The N-hydroxysuccinimide (NHS) ester is spontaneously reactive with primary amines (—NH2), providing for efficient PEGylation of proteins, peptides and other amine-containing molecules or surfaces.


  • NHS-activated for efficient PEGylation of primary amines at pH 7-9; reaction of NHS-ester group results in formation of stable, irreversible amide bonds
  • Fully characterized PEGylation reagents with defined PEG chain lengths; molecules of discrete molecular weight for consistency of performance in protein-modification applications
  • Provided as a series of 4, 8, 12 and 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