The α-sarcin domain of 285 rRNA is involved in protein synthesis reaction catalyzed by ribosomes. It was demonstrated that trichosanthin is an RNA N-glycosidase, and a new method for RNA N-glycosidase assay was preliminarily established. Trichosanthin cleaves the super-coiled double-stranded DNA to produce nicked circular and linear DNA, and other RNA N-glycosidases also have this endonucleolytic activity. The same molecular mechanism may exist in the action of trichosanthin on 28S rRNA. supercoiled DNA and HIV-1 RNA.