2,4,6-Trinitrobenzenesulphonic Acid

2,4,6-Trinitrobenzenesulfonic acid (TNBS) is a reagent and hapten. It reacts with free amino groups in peptides and proteins to produce a compound that absorbs at 335 nm and has been used in this way for the quantification of free amino groups during protein hydrolysis. As a hapten, TNBS binds to high-molecular weight molecules, such as proteins, inducing them to become immunogenic. In this way, it has commonly been used to induce colonic inflammation in laboratory animals as a model of inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis.