| The naturally occurring antibiotic ;Extensive multidimensional NMR analysis afforded unambiguous assignments of all the proton and carbon-13 resonances of F-244.;The biosynthesis of F-244 in Fusarium sp. ATCC 20788 was investigated by incorporation of isotopically labelled precursors such as acetate and methionine into growing cultures. Separation and purification of the resulting labelled F-244 was followed by NMR analysis to determine the location of label.;The results show that F-244 is a polyketide metabolite derived from 7 acetate units arranged in a typical "head-to-tail" fashion; the three methyl groups and the carbon of the hydroxymethyl moiety are derived from L-methionine. The carbon-oxygen bonds at C;To test this hypothesis, several of the potential intermediates, both as free acids and as N-acetylcysteamine thioesters, with strategically placed deuterium or carbon-13 labels, were synthesized and fed to growing cultures of Fusarium sp. ATCC 20788.;The results of feeding experiments using deuterium labelled putative intermediates showed that none of these precursors was incorporated intact. When the carbon-13 labelled intermediates were used, the... |
