Formation of roseoflavin from guanine through riboflavin.

A synthesis of roseoflavin by Streptomyces davawensis from guanine through riboflavin was demonstrated. The lines of evidence are (1)incorporations of 14C of [2-and U-14C] guanine and [2-14C] riboflavin into roseoflavin, (2) no incorporation of 14C of [8-14C] guanine into roseoflavin, (3) localizations of 14C in roseoflavin, and (4) a decrease of specific radioactivity of roseoflavin formed from [2-14C]guanine on addition of riboflavin to the culture. The 14C atoms in roseoflavin formed were localized by radioactivity analysis of the NaOH-hydrolysis products, i.e., urea and 1,2-dihydro-6-methyl-7-dimethylamino-2-keto-1-D-ribityl-3-quinox-alinecarboxylic acid (QC), a new substance. These hydrolysis products were identified by the isolation of dixanthylures, decomposition with urease, and from the properties of QC and QC tetraacetate isolated. These finding suggest that the pyrimidine ring of guanine is conserved in the formation of roseoflavin from guanine through riboflavin.