1. Chemical structure

Molecular formula: CH₃O-(CH₂CH₂O)ₙ-CH₂CH₂ -OMS

mPEG: methoxy polyethylene glycol (methoxy PEG), providing hydrophilicity and biocompatibility.

OMs: mesylate (-OSO₂CH₃), as an active leaving group, is prone to substitution reactions with nucleophiles (such as amino and thiol groups).



2. Characteristics

Reactivity: The methanesulfonate group (-OMs) has a high electronegativity and can undergo nucleophilic substitution reactions with primary amines (-NH₂), thiol groups (-SH), etc., forming stable covalent bonds (such as amino-PEG or sulfide bonds).

Water solubility: Thanks to the strong hydrophilicity of the PEG chain, it is readily soluble in water and most organic solvents (such as DMSO, DMF).

Molecular weight range: Usually 500 Da to 20 kDa, and different chain lengths can be selected according to requirements.



3. Application fields

Drug modification

It is used for PEG drugs (such as proteins, peptides, and small molecules) to extend their half-life and reduce immunogenicity.

React with the amino groups in drug molecules to form PEG-drug conjugations.

Biological coupling

Modify antibodies, nucleic acids or other biomolecules to improve their solubility and stability.

Polymer synthesis

As a macromolecule initiator or end-group functionalizing reagent, it participates in polymerization reactions (such as ring-opening polymerization).



4. Advantages and Precautions

Advantages:

The reaction conditions are mild (it can be carried out at room temperature or low temperature).

Methyl sulfonate ester is more stable than brominated or iodinated PEG and is easier to store.

Notes:

It should be stored away from moisture to prevent the hydrolysis and failure of mesylate ester.

The reaction should be carried out in a weakly alkaline (pH 7-9) buffer (such as PBS) or an organic solvent.