Mitsuda H, Nakajima K, Yamada Y
J Biol Chem. 1978 Apr 10;253(7):2238-43.
Studies were carried out to determine possible intermediates involved in the biosynthetic pathway of riboflavin, using resting cells of a riboflavin-adenine-deficient mutant, Bacillus subtilis AJ1988. The cells excreted 6,7-dimethyl-8-ribityllumazine, the end product in the biosynthetic pathway, into the incubation medium in large amounts. The addition of glyoxal caused a large accumulation of a green fluorescent compound; an inverse relation was observed between the formation of the lumazine and the concentration of glyoxal. Furthermore, added [2-14C]guanine effectively incorporated into the lumazine and the fluorescent compound in the same specific activity during incubation. The fluorescent compound was isolated, purified, and identified by paper chromatographic, fluorometric, and spectrophotometric analyses. It was proved to be 8-(1'-D-ribityl)lumazine, which appeared to have been formed by a reaction between glyoxal and a possible intermediate in the cells. Accordingly, 4-(1'-D-ribitylamino)-5-amino-2,6-dihydroxypyrimidine was concluded to be an immediate precursor of 6,7-dimethyl-8-ribityllumazine.
利用核黄素 - 腺嘌呤缺陷型突变体枯草芽孢杆菌AJ1988的静息细胞进行了研究，以确定参与核黄素生物合成途径的可能中间体。这些细胞将生物合成途径的终产物6,7 - 二甲基 - 8 - 核糖基卢马嗪大量分泌到培养液中。乙二醛的添加导致一种绿色荧光化合物大量积累；观察到卢马嗪的形成与乙二醛浓度之间呈反比关系。此外，添加的[2 - ¹⁴C]鸟嘌呤在培养过程中以相同的比活性有效地掺入到卢马嗪和荧光化合物中。通过纸色谱、荧光分析和分光光度分析对荧光化合物进行了分离、纯化和鉴定。结果证明它是8 - (1'-D - 核糖基)卢马嗪，它似乎是由乙二醛与细胞中的一种可能中间体反应形成的。因此，得出结论4 - (1'-D - 核糖基氨基)-5 - 氨基 - 2,6 - 二羟基嘧啶是6,7 - 二甲基 - 8 - 核糖基卢马嗪的直接前体。
