Ricin toxin from castor seeds has been well established as a cytotoxin interferring with ribosomal functions.The activity of any protein generally is conferred by the domains present in it. This made scientists to probe the domains and  critical amino acids for the cytotoxic activity of ricin. Researchers in USA have made molecular analysis of castor bean toxin at the genetic level where tools of genetic engineering are exploited to address their domain mapping studies.The experimentation involved synthetic mutation process in genetic determinants of ricin protein for hypothetical amino acid, glutamate to alanine which basically is distant to the former constituent in terms of its physio-chemical properties and makes it an ideal substituent to understand the magnitude of glutamate in the ricin function.Their data in the end from mutant protein’s activity indicated that the target glutamate is not of primary significance in ricin’ toxicological function.

Domain mapping by mutations is an iterative process but an intense technique to make a complete scrutiny of the sub components in a complex molecule and their implications to the ultimate emergence of functions from bulk.

For reading:http://mcb.asm.org/cgi/reprint/9/11/5012.pdf