Probably participates in a plant defense mechanism. Inhibitory effect on the growth and development of larvae from Helicoverpa punctigera. Has hemolytic activity. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Kalata-B2 is a cyclic peptide which occurs in three forms: with unmodified Trp, with Trp oxidized to form N-formylkynurenine and with Trp oxidized to form kynurenine. Oxidation is enhanced by exposure to sunlight. With N-formylkynurenine. With kynurenine. Belongs to the cyclotide family. Moebius subfamily. The oxidation forms of Trp-89, Trp-143 and Trp-197 are subject of controversy and could be the artifactual results of sample handling.