So enough to kill about 2.5 million people at 0.2mg each
easy-peasy.
We had to get special dispensation from the government (
via then Senator Ted Kennedy) to have
that much of the stuff.
We actually had a very interesting and elegant way to irreversibly modify the carbohydrate-binding B chain, essentially by affinity labeling, to reduce the non-specific cytotoxicity of intact (two chain) ricin when attached to (in our case) a monoclonal antibody designed to target cancer cells (B cell lymphomas, in the case of the proof-of-concept drug). Long story short, it was very promising in animal studies and in Phase I trials, but failed in pivotal trials. I'll spare all y'all the details, as there was
absolutely no vinyl involved. Cyanuric chloride, yes, but no vinyl chloride.
Ricin is a really elegant molecule, designed by evolution
to kill cells with incredible efficiency. The B chain binds to cell surface carbohydrate (my specialty, you see) and is involved in the internalization and intracellular targeting of the toxic "payload". The toxic part of ricin (the A chain) is an enzyme (a glycosidase, interestingly enough) that cleaves a specific residue in one of the RNA molecules that makes up the ribosome (the protein synthesis machinery) in eukaryotes, so it could catalytically kill a cell by halting protein biosynthesis. As my boss used to say, one molecule of ricin can kill a cell.
The LD50 ("lethal dose" at which 50% of a cohort of lucky animal "volunteers", in this case, mice) for injected ricin is ca. 1 microgram per kg of, umm,
victim mass.
I should mention that ricin (found in castor beans) and other related plant toxins (e.g., abrin, modeccin, and the toxic lectin of mistletoe) are believed to function as a sort of proto-immune system in seeds to protect the seed - or perhaps more to the point, ultimately the generic material therein - from environmental pathogens (i.e., threats) such as molds.
www.company7.com
