Thermo Scientific Pierce N-Ethylmaleimide (NEM) is a small compound that forms a stable co-conjugate with sulfhydryl groups. valent thioether bonds (such as reduced cysteine) so that they can be permanently blocked to prevent disulfide bond formation.

Features of N-ethylmaleimide (NEM):

•Permanently blocks sulfhydryl groups to prevent disulfide bond formation.
•Monitor the reaction by measuring the decrease in absorbance at 300 nm
•Block sulfhydryl-containing reagents that interfere with enzyme assays

N-Ethylmaleimide (NEM) is a Alkylating reagent for sulfhydryl reactions. At pH 6.5-7.5, the maleimide reaction is specific for sulfhydryl groups; however, above pH 7.5, reaction with amino groups occurs. The maleimide group reacts with the sulfhydryl group by nucleophilically attacking the thiolate anion on a double bonded carbon. When enough thiol groups are blocked, the reaction can be monitored by measuring the decrease in absorbance at 300 nm as the double bond becomes a single bond. The resulting thioether group is irreversible and terminates in the ethyl group, blocking or covering the thiol group.

Related products
Pierce™ MMTS Sulfonate ester)