alpha-Amanitine
Alpha-amanitin is a heterodetic cyclic peptide consisting of eight amino acid residues and containing a thioether bridge between a cysteine and a tryptophan residue. It is found in a number of poisonous mushrooms, including Amanita phalloides (the death cap), Galerina marginata, and and Conocybe filaris. It has a role as a mycotoxin and an EC 2.7.7.6 (RNA polymerase) inhibitor.