Conversion of 4‐thiouridine residues in tRNA into radioactive N‐4‐methylcytidine for sequence analysis

A simplified method for study of RNA conformation - reaction of formylmethionine transfer RNA with [14c]methylamine-bisulfite

“…One peak was obtained after modification of the RNA which did not originate from a cytosine residue. We believe this resulted from the conversion of the 4-thiouridine at position 8 to N -methylcytidine by the combined action of bisulfite, oxygen, and methylamine.12 15 In our earliest runs, we observed a nunber of additional radioactive peaks not coincident with ultraviolet absorbtion. These artifacts were largely, but not completely, eliminated by briefly incubating the tRNA with cold methylamine-bisulfite before adding the radioactive reagent.…”