title: A 15N nuclear magnetic resonance study of the biosynthesis of quinoxaline antibiotics.
abstract: Uniformly 15N-labelled triostin A and echinomycin have been prepared by growing the producing organisms on enriched media and their 15N nuclear magnetic resonance spectra partially assigned by a combination of nuclear Overhauser effect and scalar coupling constant measurements. Selective feeding experiments using unlabelled L-tryptophan-supplemented media have shown that N-1 and N-4 of the quinoxaline rings have their origins in the indole and amino groups of tryptophan, respectively.
mesh_terms: D004448:Echinomycin / Q000096:biosynthesis*; D009682:Magnetic Resonance Spectroscopy; D009587:Nitrogen Isotopes; D011810:Quinoxalines / Q000096:biosynthesis* / Q000378:metabolism; D013302:Streptomyces / Q000378:metabolism*
chemical_list: D009587:Nitrogen Isotopes; D011810:Quinoxalines; C031945:triostin A; D004448:Echinomycin