N-hydroxysuccinimide

N-hydroxysuccinimide (NHS) is chemical used to form semi-stable, but reactive, esters from carboxylic acids. Such NHS esters can be stored for a relatively long time if kept cold and dry. NHS is typically used in conjunction with a dehydrating reactent, often a carbodiimide such as EDAC, DCC or DIC. A very similar compound, sulfo-NHS, which contains an SO3- group on one of the two aliphatic carbons, is often used instead.