On the Biosynthesis of Toxoflavin, an Azapteridine Antibiotic Produced by Pseudomonas cocovenenans
Bruce Levenberg 1 and Sandra N. Linton 1
From the
1 From the Department of Biological Chemistry, The University of Michigan, Ann Arbor, Michigan
Methods are described for the study of the biosynthesis of the azapteridine antibiotic, toxoflavin, in cultures of Pseudomonas cocovenenans. The formation of this compound has been obtained not only under conditions of growth of the organism in a chemically complex medium, but also with washed cell suspensions under chemically defined culture conditions.
Isotopic tracer experiments have shown that (a) the pyrimido moiety of the antibiotic originates in the corresponding portion of the ring structure of a purine derivative at an oxidation level no higher than xanthine; (b) the two N-methyl substituents may be derived from methionine methyl groups; and (c) carbon atom 8 of the imidazole moiety of the purine precursor is expelled during biosynthesis, with the subsequent insertion of the aminomethyl group of glycine to complete the as-triazine ring portion of toxoflavin.
Stimulation of toxoflavin synthesis under chemically defined conditions has been achieved by the inclusion of purine derivatives, methionine, and biochemical sources of glycine in the medium.
The results are discussed in terms of their relationship to the general problem of the biological transformation of purines to pteridines.
Submitted on August 6, 1965
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