Abstract
4-Ribitylamino-5-aminouracil (II), which is regarded as an intermediate in the biosynthesis of riboflavin, was synthesized and the formation of 6, 7-dimethylribolumazine (III) and riboflavin (IV) was examined in three cases, in which a mixture of (II) and a crude enzyme solution prepared from Er. ashbyii, a mixture of (II) and acetoin, and a mixture of (II), acetoin, and a crude enzyme solution were each incubated at 37°. In the first two cases, the formation of (III) and (IV) was not observed, but in the lase case the formation of a green fluorescent substance and increase of (IV) were recognized. The green fluorescent substance was confirmed to be (III) from its Rf values and ultraviolet spectrum. From these results, it seems reasonable to think that riboflavin which is an isoalloxazine derivative is biosynthesized in the mycelium of Er. ashbyii from a pyrimidine compound (II) through a pteridine compound (III).
