4-hydroxy-5-iodo-3-nitrophenylacetyl-epsilon-aminocaproic acid anion

A synthetic small molecule, the 4-hydroxy–5–iodo–3–nitrophenylacetyl–epsilon–aminocaproic acid anion (often abbreviated as NIP-cap or NIP aminocap) is a derivative of nitrophenol compounds. It is primarily used in immunological research as a model hapten for studying antibody specificity and affinity maturation. The compound is structurally related to the well-known NP (4-hydroxy–3-nitrophenylacetyl) hapten but contains an iodine atom at the 5-position, which increases its heteroclitic binding properties—meaning certain antibodies raised against NP bind with higher affinity to this iodinated analog. This property has made it valuable in studies of B cell responses, antibody diversity, and immune system genetics in mice[1][3][5]. There are no known therapeutic indications or clinical uses; it is not approved for human use.

Other names

6-[2-(4-hydroxy-3-iodo-5-nitrophenyl)ethanoylamino]hexanoate[2]