Purification and Biochemical Characterisation of Ricin from Castor Seeds

Ricin is a highly toxic plant toxin of Ricinus comtnunis seeds, commonly known as castor seeds. The toxin was extracted and purified using affinity and size exclusion chromatography. The purity of ricin was evaluated by the sodium dodecylsulphate-polyacrylamide gel electrophoresis. Purified ricin gives a single band under non-reduced condition and two bands under reduced condition. The molecular weight of ricin was 65,0000 approx. The subunit structure of ricin on treatment with p-mercaptoethanol (1 %) at molecular level revealed that the reducing agent converts ricin into two peptides. The molecular weight of these two peptides was estimated to be 34000 and 32000. The western-blot analysis revealed two dots for its two peptides in 29 kDa to 36 kDa regions. The heamagglutination litres for ricin and Ricinus communis agglutinins were 1:8 and 1:256. The purity of purified ricin was further confirmed by the electrophoresis and the western-blot analysis. The Indian variety of castor seeds, known as Ricinus communis used in this study, contains approx. 0.12 per cent ricin.