SUMMARY: A diazotizable amine and hypoxanthine accumulate in cultures of Yeast 47 grown in a defined medium containing added methionine and suboptimal biotin. Amine accumulation is depressed by the presence either of added adenine, or of certain amino acids, of which aspartate, norleucine, norvaline and threonine are the most effective. The amine differs from 4-amino-5-imidazolecarboxamide and the corresponding amidine. Spectrophotometric measurements suggest that the amine lacks the completed 6-membered ring structure of the purine skeleton, but it has biological activity in lieu of adenine for the adenine-requiring Yeast 19, and of guanine for a strain of

Hypexanthine substitutes for adenine in the growth of Yeasts 19 and 47, and for adenine + guanine in , which suggests that hypoxanthine is a bio-precursor of both adenine and guanine. The accumulation of hypoxanthine in cultures of Yeast 47 may thus be the result of a synthetic block, conditioned by biotin deficiency, which prevents the conversion of hypoxanthine to adenine and guanine. The possible relationships between diazotizable amine and hypoxanthine are discussed.

Chamberlain, Cutts & Rainbow (1952) reported the conditions under which Yeast 47 formed pigment and accumulated a diazotizable amine in liquid medium. This paper reports a study of the constituents present in amine-containing concentrates prepared from culture fitrates of Yeast 47.


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