N-Ethylmaleimide TCI E0136

N-Ethylmaleimide with CAS number 128-53-0 is a classic reagent in the field of chemical biology, widely recognised for its ability to react specifically with thiol groups. The compound belongs to the maleimide family, characterised by an unsaturated ring that readily accepts nucleophilic attack through a Michael addition reaction. In routine biochemical laboratory practice, this reagent is used to block cysteine residues on proteins, allowing researchers to establish the role of sulfhydryl groups in enzyme activity, protein structure, and the biological reaction pathways under investigation in a systematic and controlled manner.

The property that makes N-Ethylmaleimide so dependable is the selectivity of its reaction toward thiols in the near-neutral pH range, which allows modification to proceed without disturbing other functional groups present on the biomolecule. The thioether bond that is formed is stable, so the modified product can be carried forward into further analysis without concern that the reaction will reverse. Its small molecular size means the reagent penetrates readily and can reach cysteine residues that are comparatively shielded. These characteristics are precisely what have made it a benchmark for comparison in many bioconjugation protocols and enzyme inhibition studies.

In Indonesian laboratories, N-Ethylmaleimide is typically found in academic biochemistry and molecular biology laboratories, university research groups, and analytical or quality-control laboratories that work with proteins and enzymes. It is generally used at the bench scale in method development and teaching contexts, where a well-documented and predictable thiol-blocking reagent is required so that experimental results remain comparable with published protocols.

• Cysteine residue blocking in proteins — the reagent reacts specifically with free sulfhydryl groups, allowing researchers to mask reactive cysteines before further treatment and confirm their contribution to protein function.
• Enzyme inhibition studies — because many enzymes depend on an active-site cysteine, controlled reaction with this maleimide helps establish whether sulfhydryl groups are essential to catalytic activity under the conditions studied.
• Bioconjugation protocol development — the stable thioether bond formed and the predictable near-neutral pH selectivity make this compound a common benchmark against which newer thiol-reactive linkers are compared.
• Investigation of protein structure and folding — selective modification of cysteine residues lets researchers probe which sulfhydryl groups are exposed and which remain shielded within the folded structure.
• Studies of biological reaction pathways — by removing free thiols from the system in a controlled way, investigators can determine which steps of a biochemical pathway genuinely depend on sulfhydryl chemistry.

• Product code: E0136

Store the container tightly closed in a cool, dry, well-ventilated place, away from moisture, heat, and incompatible materials, following the conditions stated by the manufacturer on the label and safety data sheet. Keep the material in its original chemically compatible container, and use clean, dry glassware or plasticware when preparing working solutions. As with any thiol-reactive laboratory chemical, handle it inside a fume hood where practical, wear a laboratory coat, safety glasses, and suitable gloves, and avoid contact with skin, eyes, and inhalation of dust. Prepare solutions fresh where the protocol requires it, label all containers clearly, and dispose of residues and contaminated consumables in line with your institution's chemical waste procedures.

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