Probably participates in a plant defense mechanism. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. This peptide occurs in both cyclic and linear forms. The linear form contains unmodified Trp-24, the cyclic peptide occurs in two forms with unmodified Trp-24, and with Trp-24 oxidized to form oxindolylalanine. Oxidation is enhanced by exposure to sunlight. Cyclic form. Linear form. With oxindolylalanine. Belongs to the cyclotide family. Moebius subfamily. The oxidation form of Trp-24 is subject of controversy and could be the artifactual result of sample handling.