Linaclotide is an orally administered, peptide agonist of guanylate cyclase 2C for the treatment of irritable bowel syndrome. Chemically, it is a heterodetic cyclic peptide and consists of fourteen amino acids. The protein sequence is as follows: Cys Cys Glu Tyr Cys Cys Asn Pro Ala Cys Thr Gly Cys Tyr. There are three disulfide bonds which are located between Cys1 and Cys6; between Cys2 and Cys10; and between Cys5 and Cys13.