The enzymatic conversion of 5-formyluracil to uracil 5-carboxylic acid.

Fink and Fink (1) have shown that Neurospora crassa mycelia convert thymidine to the uracil and cytdsine of RNA without fragmentation of the pyrimidine ring. A cell-free system from Neurospora catalyzes several reactions which appear (l-3) to be involved in this pathway effecting the removal of the methyl group of thymidine. These reactions are the conversions of thymidine to thymine ribonucleoside (4), thymine to 5-hydroxymethyluracil (5), and the latter compound to 5-formyluracil (6j.l In studies with more active preparations of this enzyme system (4), the 5-formyluracil, which was generated, appeared occasionally to be converted to a very small amount of a new compound. This report documents the enzymatic conversion of 5.formyluracil to uracil5-carboxylic acid.