A ribosome-inactivating protein from Amaranthus viridis

An antiviral protein purified from the leaves of Amaranthus viridis was named amaranthin. The in vivo antiviral activity of amaranthin was confirmed in tobacco mosaic virus (TMV) infection test on Nicotiana glutinosa leaves. The molecular mass of the amaranthin was estimated about 30 kDa by SDS-PAGE and the pI was measured as 9.8 by isoelectric focusing (IEF) analysis. Cytotoxicity of the amaranthin using in vitro translation inhibition assay was similar to that of pokeweed antiviral protein (PAP) with IC50 of 25 pM. Depurination activity (N-glycosidase activity) against animal rRNA was also confirmed.