Characterization of ricin heterogeneity by electrospray mass spectrometry,capillary electrophoresis, and resonant mirror

Electrospray mass spectrometry (ES/MS), capillary-zone electrophoresis (CZE ), capillary isoelectric focusing (CIEF), and multianalyte resonant mirror are used to evaluate the heterogeneity of samples of ricin toxins extracted from five horticultural varieties of Ricinus communis seeds: R. communis z anzibariensis, carmencita, impala, sanguineus, and gibsonii. The investigat ion is also extended to the geographical provenance of the beans. Combining mass spectrometry, CE techniques, and resonant mirror results in a powerfu l analytical tool capable to characterize and differentiate between differe nt varieties of ricin toxins. Each technique complements the others, adding another level of information. This study reveals a large extent of heterog eneity for each cultivar, demonstrating that ricin toxins consist of a seri es of glycosylated proteins most likely originating from a multigene family . By combining these techniques, it is possible to differentiate between za nzibariensis and the other four varieties, and that variations in the funct ional characteristics may be observed between the different cultivars. This study demonstrates that knowledge of the variety of R. communis beans used and their geographical provenance is essential before any type of investig ation of ricin toxins is carried out. Consequently, any unusual behavior ob served can only be attributed to that particular cultivar studied and not a utomatically extended to include all R. communis varieties. (C) 2000 Academ ic Press.