N-Ethylmaleimide is a protein thiol modifier which inhibits apoptotic DNA fragmentation. It is a sulfhydryl reagent and finds application in experimental biochemical studies as well as in enzymology. It is involved in the modification of cysteine residues in proteins and peptides. It acts as a Michael acceptor and reacts with nucelophiles like thiols. It is employed in the inhibition of Mg²⁺ dependent internucleosomal DNA fragmentation.

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