n-ethylmaleimide

N-Ethylmaleimide (NEM) is a small molecule derived from maleic acid and classified as a maleimide. It is a highly reactive Michael acceptor that selectively alkylates thiol (sulfhydryl) groups in proteins and peptides—most notably cysteine residues—forming stable thioether bonds. This reaction is virtually irreversible under physiological conditions. NEM acts as an irreversible inhibitor of all cysteine peptidases by covalently modifying the active site thiol group. It has been widely used in biochemical research to probe the functional role of protein thiols and to inhibit enzymes such as deubiquitinases and certain kinases. In addition to its use in protein modification studies (e.g., blocking de-sumoylation or DNA fragmentation), it serves roles in bioconjugation chemistry for attaching biomolecules to surfaces or other molecules and has applications in polymer synthesis and diagnostics[1][4][5][6][7].

Other names

n-ethylmaleimideethylmaleimide1-ethyl-1H-pyrrole-2,5-dioneN-EthylmaleinimideNEMI/NEMusafb-121usafb121usafb 121