ABSTRACT
Ricin is a potent protein toxin synthesized in the seeds of the castor bean plant, Ricinus communis. Castor beans are cultivated worldwide and provide an abundant natural source for the toxin, which is readily isolated from the castor meal or cake after the oil is extracted [1,2]. Puried ricin is water-soluble and moderately heat-resistant, and retains its activity across a wide pH range [3-5]. It has long been considered a signi- cant threat for use in biological warfare and bioterrorism, in large part due to its stability and ease of production [3-8]. Studies conducted during World War II yielded a crystalline form of ricin with much higher toxicity than any previous crude extract [4,9,10]. Although the crystalline preparation was still relatively heterogeneous, subsequent renements in extraction methodologies have since enabled high yield production of pure ricin containing no contaminating hemagglutinating or proteolytic activity. Recombinant ricin has also been produced in transgenic plants [11-14].
