5-Aminoimidazole and its Riboside from Biotin-Deficient Yeast

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Abstract
A purified preparation of the "amine" which accumulated in the medium during the growth of a strain of Sacchoromyces cerevisiae (yeast 47) under conditions of partial biotin-deficiency contained two compounds, one of which was chromatographically and electrophoretically identical with synthetic 5-aminoimidazole. Both compounds gave identical colors on diazo-tization and coupling in the Bratton and Marshall reaction and on treatment with the Pauly imidazole reagent. The-other, and major, component of purified "amine" was shown to be 5-aminoimidazole riboside by its conversion to the free base and ribose on incubation with a bacterial nucleosidase. Synthetic 5-aminoimidazole gave analytical figures for fromate, NH3-N and total-N similar to those previously obtained for purified "amine". Evidence was obtained that resting organisms of a mutant Escherichia coli converted "amine" and synthetic 5-amino-idazole to 5-amino-4-imidazole-carboxamide. One of the adenine derivatives which accumulated instead of "amine" and hypoxanthine in a medium supplemented with aspartate was tentatively identified as thiomethyladenosine.