Jequirity
Balck-eyed Susan (Abrus precatorius)
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| Abrus precatorius |
The Jequirity, also called Black-eyed Susan, Rosary Pea or Indian Licorice (Abrus precatorius), is a legume with long pinnate-leafleted leaves, whose seeds are used as beads and in percussion instruments. The seed is highly poisonous but is unlikely to harm if swallowed raw and unbroken, as the seeds have a hard seed coat.
The toxin present in Abrus precatorius is a toxalbumin called abrin (closely related to ricin from castor beans). It consists of two protein chains: A and B. The B chain is abrin's "ticket" into the cell?it bonds to certain transport proteins on cell walls, which then transport the abrin into the cell. Once inside the cell, the A chain goes to work. It is an enzyme which denatures rRNA by removing a specific amino acid from its place (the 26S position on the rRNA chain), making protein synthesis impossible. One molecule of abrin will inactivate up to 1,500 ribosomes per second. Symptoms are identical to those of ricin, except that the fatal dose of ricin is approximately 75 times greater than the fatal dose of abrin. Abrin can kill with a circulating amount of less than 3 mcg (micrograms).
The seeds of Abrus precatorius are much valued in native jewelry for their bright coloration. The third of the bean with the hilum (attachment scar) is black, while the rest is bright red, suggesting a ladybug. Jewelry-making with jequirity seeds is dangerous, and there have been cases of death by a finger-prick while boring the seeds for beadwork.
