Studies on 5-hydroxyuridine (isobarbituridine): X. Isolation and tentative identification of 5-hydroxymethyluridine from ribosomal RNA.

Yeast ribosomal RNA was hydrolyzed to its constituent nucleosides with the aid of snake venom and bacterial alkaline phosphatase. Lyophilized hydrolysate was labeled with radioactive 5-hydroxyuridine and applied to partition chromatography. It was found that some components of rRNA are held on the column and can be eluted with water. Eighty-nine percent of the label, a large portion of cytidine, and several unidentified compounds were found in the water wash. The direct application of the wash concentrate to ascending paper chromatography in saturated butanol-H2O resulted in the separation of three distinct UV-absorbing bands. Further resolution and characterization of one band of unidentified material revealed the presence of an additional nucleoside. On the basis of chromatographic and electrophoretic behavior and UV-absorption spectra, it was tentatively identified as 5-hydroxymethyluridine.