Claim: Bioassay (an analytical method to determine concentration or potency of a substance by its effect on living cells or tissues) guided fractionation and chromatography identified stromatoxin, a peptide consisting of 34 amino acids that belongs to the structural family of ‘inhibitor cystine knot’ (the only fold in the cystine knot motif) spider peptides, as the functional component.
Evidence: Knottins are one of three folds in the cystine knot motif; the other closely related knots are the Growth Factor Cystine Knot (GFCK) and the Cyclic Cystine Knot (CCK; cyclotide).