Ricin molecule

Rights Managed

SS2175807

SC3204

Ricin. Computer model of a molecule of the toxic protein ricin. It comprises two amino acid chains, termed A (upper right) and B (lower left). The A- chain is toxic, inhibiting protein synthesis in cells. It is carried into cells by the non-toxic B-chain. Ricin is derived from the seeds of the castor oil plant (Ricinus communis). Less than a milligram is enough to kill an adult. Inhaling ricin causes coughing, pulmonary oedema and death. If ingested, it causes gastroenteritis, liver and kidney damage and death from circulatory failure. There is no antidote. Bioterrorists could use it. The protein (529 amino acids, coloured) has alpha helices (cylinders) and beta sheets (arrows).

Dr. Tim Evans / Science Source

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