N-Ethylmaleimide
（重定向自Ethylmaleimide）
![](/Images/godic/202501/11/N-ethylmaleimide.svg5303.png")
![Mechanism of irreversible inhibition of a cysteine peptidase with NEM.](/Images/godic/202501/11/NEMmech5303.jpg")
N-Ethylmaleimide (NEM) is an organic compound that is derived from maleic acid. It contains the imide functional group, but more importantly it is an alkene that is reactive toward thiols and is commonly used to modify cysteine residues in proteins and peptides.