title: Identification of ricin in crude and purified extracts from castor beans using on-target tryptic digestion and MALDI mass spectrometry.
abstract: Ricin is a toxic protein produced in the seeds of the castor bean plant. The toxicity of the protein and the ease in which it can be extracted from the seeds makes it a potential biological warfare agent. There has been extensive work in the development of analytical techniques that can identify the protein robustly and rapidly. On-target tryptic digestion and MALDI MS was used to distinguish ricin from bovine serum albumin and three other type 2 ribsome-inactivating proteins (RIPs), abrin, agglutinin (RCA(120)), and viscumin, using the peptide mass fingerprint. The sequence coverage obtained was enhanced using methanol-assisted tryptic digestion and was particularly useful for the detection of these toxins in complex matrixes. When used in conjunction with intact protein MALDI mass measurement, a positive identification of ricin (or any of the other RIPs) was achieved including confirmation of the integrity of the disulfide bond between the A and B chains. This applicability of this methodology was demonstrated by the identification of ricin in a typical "crude white powder" that may be illicitly produced in a clandestine lab. The analysis on the solubilized sample using this method can be undertaken in around an hour with minimal sample preparation.
authors.affiliation: Human Protection and Performance Division, Defence Science and Technology Organisation, Fishermans Bend, Victoria, Australia, 3207. craig.brinkworth@dsto.defence.gov.au
authors.forename: Craig S
authors.initials: CS
authors.lastname: Brinkworth
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002367:Ricinus communis / Q000737:chemistry*; D002417:Cattle; D008969:Molecular Sequence Data; D010449:Peptide Mapping / Q000191:economics / Q000379:methods*; D010936:Plant Extracts / Q000032:analysis / Q000302:isolation & purification; D054790:Ribosome Inactivating Proteins, Type 2 / Q000032:analysis; D012276:Ricin / Q000032:analysis* / Q000302:isolation & purification; D012710:Serum Albumin, Bovine / Q000032:analysis; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000191:economics / Q000379:methods*
chemical_list: D010936:Plant Extracts; D054790:Ribosome Inactivating Proteins, Type 2; D012710:Serum Albumin, Bovine; D012276:Ricin