Abstract
A modification of the known method for obtaining radioactive fingerprints from non-radioactive nucleic acids by labelling a digest with 5'-hydroxyl polynucleotide kinase and [gamma-32P]-ATP has been applied to RNase T1 digests from various high molecular weight virus RNAs and to ovalbumin mRNA. Fractionation of the resultant [32P]-labelled T1 RNase digests by two-dimensional polyacrylamide electrophoresis demonstrates that in the case of virus RNAs, the fingerprints thus obtained are very similar to those derived from uniformly labelled RNAs. The value of this technique is that it requires only 1-5 microgram of purified virus RNA and at least three orders of magnitude less radioactivity than is routinely employed in preparing uniformly labelled RNA.