The 5'-termini of the oligonucleotides from ribonuclease T 1 digested E. coli ribosomes

Oligonucleotides remaining in the 70s $\text{Escherichia}\text{coli}$ ribosomal particles after varying degrees of digestion with ribonuclease T₁ were phosphorylated with polynucleotide kinase in the presence of γ-labeled³²P-ATP. The resulting radioactively labeled RNA molecules were further digested with pancreatic ribonuclease and analyzed by a two-dimensional finger-printing technique. The numbers of labeled oligonucleotides were proportional to the duration of T₁ digestion; most of these oligonucleotides yielded ¹pAp and/or ¹pCp as their 5′-end groups upon alkaline hydrolysis.