Chromatographic changes in specific tRNAs after reaction with cyanogen bromide and sodium periodate

Chromatography of chemically modified tRNAs has been used as a preliminary means of locating the nucleoside Q in tRNA species. The technique requires only milligram quantities of unfractionated tRNA and relies on altered chromatographic elution of the radioactive aminoacyl-tRNA after reaction with either CNBr or NaIO4. The nucleoside Q has previously been shown to react with both CNBr and NaIO4 resulting in the loss of its positive charge. Crude tRNA is reacted with CNBr, aminoacylated with a specific radioactive amino acid and co-chromatographed with an unreacted tRNA charged with the same amino acid containing a different radioactive label. Similarly aminoacyl-tRNA is reacted with NaIO4 and co-chromatographed with unreacted aminoacyl-tRNA. Specific alterations in elution of aminoacyl-tRNAs after these reactions provide good evidence for the presence or absence of Q.