5-methoxyuridine: a new minor constituent located in the first position of the anticodon of tRNAAla, tRNAThr, and tRNAVal from Bacillus subtilis.

The sequences of the anticodon of tRNAAla, tRNAThr, and tRNAVal from Bacillus subtilis W 168 were N-G-C, N-G-U, and N-A-C, respectively. A new minor constituent, N, occupied the first position of the anticodon of each tRNA. N was indentified as 5-methoxyuridine (mo5U, Figure 1) by comparison of its UV absorption spectra, Rf values in thin-layer chromatography using several solvent systems and mass spectra with those of chemically synthesized specimen.