Chemical Modification of Cytosine Residues of tRNA^Val with Hydrogen Sulfide (Nucleosides and Nucleotides. XL)

The conversion of cytosine residue of transfer ribonucleic acid (tRNA) to 4-thiouracil residues was carried out with a hydrogen sulfide-pyridine-water system. In the case of tRNA^Val from mouse cells, the cytosine moieties located in unpaired and looped-out regions of the molecule, such as the anticodon and CCA-end regions, were converted. This result shows that the secondary and tertiary structures of tRNA are maintained even in medium containing liquid hydrogen sulfide and pyridine, and hence, this system should be suitable for studies of the higher-order structure of nucleic acids.