Lectins ricin

Endo, Y. and Tsurugi, K. (1987) RNA N-glycosidase activity of ricin A-chain. Mechanism of action of the toxic lectin ricin on eukaryotic ribosomes. J. Biol. Chem. 262, 8128-8130. 

Olsnes, S. and Saltvedt, E., 1975. Conformation-dependent antigenic determinants in the toxic lectin ricin, J. Immunol., 114, pp. 1743-1748. 

Lee RT, Gabius H-J, Lee YC. The sugar-combining area of the galactose-specific toxic lectin of mistletoe extends beyond the terminal sugar residue comparison with a homologous toxic lectin, ricin. CarbohydrRes 1994 254 269-276. 

For example, the P-trefoil fold of CBM13 is classified into the Ricin-B-like family along with a bona //de lectin (ricin toxin B-chain) [57]. CBM42 also has structural similarity to ricin toxin B-chain, binding to small sugar units and displaying multivalency [58]. 

Lectin toxicity - nausea, diarrhea, headache, confusion, dehydration, death Wisteria, castor bean (Ricinus communis) Lectins bind to cell surfaces Ricin - blocks protein synthesis, very toxic, 5 to 6 beans can kill a child... 

Other approaches to induce gastrointestinal discomfort have far more serious toxic effects. The chemical colchicine stops cell division (an antimitotic), producing severe nausea, vomiting, and dehydration, which can lead to delirium, neuropathy, and kidney failure. On the other hand, colchicine is used in the treatment of gout and has been studied as an anticancer agent because it stops cell division. Most toxic of all are plants that produce lectins, and the most toxic of these is the chemical ricin produced by castor beans. Only 5 to 6 seeds are necessary to kill a small child. Fortunately, following oral consumption much of the ricin is destroyed in the stomach. Ricin is extremely effective at stopping protein synthesis, so much so that direct exposure to only 0.1 pg/kg can be fatal. 

N.A. Ricinoleic acid, ricin, ricinine, lectins.99 The seeds are toxic. Laxative, prompting a bowel movement. 

Because they are easily accessible, glycans displayed on the surface of mammalian cells provide enormous opportunities to bind to many microbial pathogens, ranging from viruses to molecular toxins and from pathogenic bacteria to parasites. In multivalent binding, multiple interactions between ligands and various receptors are common (Fig. 16.1). One representative example is ricin—a versatile and durable A-B-type toxin—in which one of the protein chains (the B chain) is a lectin that interacts and binds terminal galactose (Gal) on the surface of eukaryotic cells with multivalent interactions to facilitate entry of the other peptide chain (the A chain) into the cell to cause cellular death via the catalytic... 

The effect of toxins such as melittin (from the honey-bee venom), myotoxin a, and cardiotoxin (from the snake venom) was investigated by vibrational spectroscopy (Pezolet et al., 1982 Faucon et ah, 1983 Liddle and Tu, 1985 Lafleur et ah, 1987). Monitoring the Raman intensity ratio I(1060)/I(1080) indicated that the lipid/melittin assemblies in DPPC are characterized by a high conformational order, little intermolecular chain-chain interaction, and a low cooperativity of the gel-like liquid crystalline phase transition. The effect of ricin, a toxic lectin, on DPPC and DPPC-cerebroside mixtures was studied by Raman and IR spectroscopy. It was suggested that ricin mainly interacts with the interfacial domains of the bilayers (Picquart et ah, 1989). 

The toxic ricin is a small protein molecule consisting of two parts, chains A and B. The B chain is similar to proteins called lectins which recognize and bind to the membranes surrounding the cells in our bodies. The B chain attaches the ricin to the cell membrane which then folds inwards so that the ricin molecule is taken inside the cell inside a bag called a vacuole. There is only one bond between the A and B chains and this now breaks. The B chain then makes a hole in the vacuole through which the A chain passes into the cell. Here it heads straight for structures called ribosomes, where proteins, many of which are vital for the functioning of our bodies, are made. The A chain then selectively removes a specific molecule (the base adenine) from the RNA in the ribosomes. RNA contains the information required to make proteins, and removal of part of the information blocks the synthesis of proteins. The cell therefore dies. One molecule of ricin may be sufficient to kill one cell. This makes it the most potent toxin known. 

Ricin was found by Stillmark in 1889 as the first plant lectin derived from the seeds of the castor plant, Ricinus communis L., a member of the Euphorbiaceae or spurge family. Other members of this family include the popular houseplants poinsettia E. pulcherrima), and the croton species. The term castor bean is used commonly to refer to both the plant and seed of R. communis. Ricinus communis commonly grows along streams and riverbeds in addition to subtropical locations high in nutrients. Ricinus communis is a coarse perennial, 10-13 m tall in the tropics, with a stem 7.5-15 cm... 

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