Determination of N-(9-( -D-ribofuranosyl)purin-6-ylcarbamoly)threonine at the picomole level in transfer-RNA

An assay has been developed for quantitation of the modified nucleoside, t⁶A, in tRNA at the pmole level. For tRNA from a variety of species, the content of t⁶A was found to be 0.18–0.25 mole %. These values lend support to the suggestion that t⁶A is located at the 3′-end of the anticodon in tRNA's whose codons begin with adenosine. Essentially no t⁶A was found in Mycoplasma sp. (Kid) tRNA which is deficient in many modified nucleosides. In the rat, no organ specific differences were found. The amount of t⁶A in Novikoff hepatoma tRNA was essentially the same as in tRNA from normal rat liver.