Thermo Scientific Pierce MS(PEG)_n reagents are methyl-terminated, polyethylene glycol compounds (n equals 4 to 24 PEG units) and TMS(PEG)₁₂ is a three-branched, polyethylene glycol compound (3 x 12 PEG units). Both are activated as NHS esters for covalent pegylation of primary amines on proteins (eg. lysines) or assay 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

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

TMS(PEG)₁₂ is the abbreviation for a branched trimethyl (TM) and succinimide ester (S) derivative of polyethylene glycol (PEG) for efficient and specific modification of primary amines. Each methyl-terminated PEG (mPEG) branch contains 12 ethylene glycol units. The three branches are attached to a 4-unit PEG stem that contains an amine-reactive N-hydroxysuccinimide (NHS) ester at the distal end. The NHS ester is spontaneously reactive with primary amines (—NH2), providing for efficient PEGylation of proteins, peptides and other amine-containing molecules or surfaces.

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.