Comparative Studies of Three Type II Ribosome-Inactivating Proteins from the Seeds of Three Species of the Genus Cinnamomum

Bodinierin, one of the major proteins in the kernels of camphor tree (Cinnamomum Bodinieri), has been identified as a novel type II ribosome-inactivating protein. Using sepharose-4B column chromatography followed by acid precipitation and ammonium sulfate precipitation, bodinierin has been purified to be homogeneous as characterized by SDS-PAGE. Bodinierin was composed of two chains (A- and B-chain) with the molecular weight of 31 and 34 kDa respectively. The reduced bodinierin showed strong inhibitory activity to protein synthesis in the rabbit reticulocyte lysate and the RNA N-glycosidase activity. The bodinierin also displayed the carbohydrate binding activity to agglutinate rabbit erythrocyte. A comparison of bodinierin with cinnamomin and porrectin that were isolated from the kernels of other species of the same genus (Cinnamomum) demonstrated that they had similar structure and biological activities, which provided phylogenetic evidence to the three species.