Studies on the biosynthesis of riboflavin. 2. Further observations on nitrogen metabolism and flavinogenesis in Eremothecium ashbyii

Abstract

Purines are known to stimulate riboflavin synthesis in the fungus Eremothecium a8hbyii (Maclaren, 1952; Goodwin & Pendlington, 1954a, b) and work with isotopes indicates that this is due to incorporation of the purine or a metabolite into the riboflavin molecule and not to an indirect effect (Plaut,

Temperature-Independent Riboflavineless Mutants of Aspergillus nidulans

“…Particularly interesting is the fact that adenosine is in no way better than the free purine in substituting the vitamin for growth. This is in accordance with the earlier observations made by McNutt (1954) and Brown, Goodwin, and Jones (1958). Histidine has been reported (Yaw, 1952) to promote flavinogenesis in E. ashbyii, but the formation of riboflavine did not directly vary with the increase in added histidine.…”

Stimulatory Effects of Purines on Flavinogenesis by Non-Growing Cell of Eremothecium ashbyii

“…However, adenine, guanine or xanthine have all been reported as the most stimulatory purine on riboflavin formation (1,(18)(19)(20).…”

The Physiology of Riboflavin Production by Eremothecium ashbyi

“…In other words, pyruvate (via acetaldehyde) is not only the substrate of the flavin enzyme but also the building material (via acetoin) for the construction of its prosthetic group. This hypothesis also explains the fact that acetate inhibits riboflavin biosynthesis but not growth on glucose medium (Brown et al 1955). Acetate is the product of the reaction catalysed by the flavin enzyme and may act as a repressor of the synthesis of this enzyme or as a source of energy for which no new enzyme is necessary when this product is added exogenously.…”