抄録
The possibility whether guanine ribonucleotidyl-(3'-5')-adenosine (GpA) is accumulated or not was studied with the use of micro-organisms such as E. ashbyii (a non-flavinogenic strain), E. coil, S. cerevisiae and N. crassa, which produce riboflavin in a trace amount. (1) In a flavinogenic strain of E. ashbyii, riboflavin formation was stimulated fivefold in the presence of glucose (1%) compared with that in the control experiment without glucose. The presence of caffeine notice-ably restricted riboflavin formation during incubation of non-growing cells with or without glucose. Moreover, the addition of caffeine to the glucose-free medium brought about marked accumulation of GpA in the cells.
(2) In a non-flavinogenic strain of E. ashbyii, riboflavin formation was remarkably slight under normal conditions. The effect of glucose and caf-feine on flavinogenesis in the same strain was much smaller than that in the flavinogenic strain except for the case of the glucose-free medium supple-mented with caffeine. However, compound (GpA) never accumulated in the strain, even under conditions permitting a large amount accumulation of GpA in a flavinogenic strain.
(3) The other organisms, E. coil, S. cerevisiae and N. crassa, did not accu-mulate GpA in the cells under the same conditions as those with a high flavinogenic strain of E. ashbyii.
(4) The results obtained indicated that a dinucleotide, GpA, is a com-pound closely related to the biosynthesis of riboflavin.
