A RAPID AND SENSITIVE METHOD TO MEASURE THE ENZYMATIC-ACTIVITY OF RIBOSOME-INACTIVATING PROTEINS

A method is described in which the adenosine-N-glycosidase activity of ribosome-inactivating proteins (RIPs) is measured using as substrate a 2251 bp [H-3]DNA obtained by PCR amplification of the 731-2981 regio n of the pBR322 plasmid, The DNA, labelled in the purine ring of adeni ne, proved a good substrate for all three RIPs tested (PAP-S, ricin an d shiga-like toxin I). The method, which measures directly the [H-3]ad enine released, is highly specific, extremely rapid and quantitative i n a wide range of RIP concentrations.