Lectin RCA-120 aus Ricinuscommunis

BeschreibungRicin is a heterodimeric ribosomeinhibiting protein consisting of an A-chain (RTA), linked by a disulphide bond to the B-chain (RTB). The total molecular weight is 66 000 Da, with the A-chain contributing 32 kDa, and the B-chain 34 kDa. The A-chain is a globular protein composed of 267 amino acids containing eight alpha helices and eight beta sheets, with the toxin’s substrate binding site located within the cleft. The B-chain is the binding lectin composed of 262 amino acids, shaped like a barbell, and has a binding site specific for membrane sugars at each end (galactose and N-acetyl galactosamine).

VerwendenRicin is a toxin found in the seeds of the castor oil plant, Ricinnus communis. The plant is cultivated commercially for its oil, but is also widespread as a weed and used as an ornamental plant. Approximately 3–5% of the waste from castor oil production is ricin. The major uses of ricin are as a chemical warfare agent, as a tool in studies of cell surface properties, and experimentally in cancer research. Ricin-A conjugate has been used experimentally in AIDS research. Low concentrations of the powders (0.3%) are marketed as a mole killer. Its preferred use seems to be as an assassin’s weapon and there are documented cases of umbrellas being used as a means of injecting ricin into human targets. It has also been found at postal facilities and mailings to a US Senator’s office.