Studies on Nucleosides and Nucleotides. V. Ultraviolet Spectrophotometric Studies on Pyrimidine Nucleosides and Isopyrimidine Nucleosides

Ultraviolet absorption spectra of pyrimidine and isopyrimidine nucleosides were compared and their difference was examined. 1-(β-D-glucopyranosyl) uracil and 3-(β-D-glucopyranosyl) uracil show practically the same spectra in the neutral region while their spectra are clearly different in alkaline solution. The spectra of 1- and 3-(β-D-glucopyranosyl)-2-thiouracils are different in both neutral and alkaline regions, and the spectra in neutral region seemed to be somewhat lacking in uniformity. These facts were found to be true in the case of thymines instead of uracils or in the presence of ribosyl group instead of glucosyl group. It follows that pyrimidine and isopyrimidine nucleosides could clearly be differentiated from their ultraviolet absorption spectra, especially from those taken in alkaline solution.