著者

通 和夫 十倉 一也 岡部 啓 江幡 光雄 大塚 英夫 松下 和弘 Lukacs G.

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.20, pp.24-31, 1976

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Sulfur-containing peptide antibiotics, siomycins (SIM) A, B, and C isolated from Streptomyces sioyaensis are known to have structures quite similar to that of thiostrepton (TST) isolated from S. azureus. The 25-MHz ^<13>C FT NMR and 220-MHz ^1H NMR spectra of TST and SIM's were determined in CDCl_3-CD_3OD (8: 2) at various temperatures to obtain structural relationships between these antibiotics. ^<13>C signals were tentatively assigned by ^1H noise decoupling, single-frequency and noise off-resonance decouplings, and partially-relaxed FT techniques and using known chemical-shift rules, the chemical shifts of amino acids reported, and those observed for thiostreptine and a quinaldic acid derivative. Their ^<13>C spectra quite similar to each other revealed the numbers of carbon atoms and dehydroalanine (Deala) residues. It was found that (1) the signals of the Val-Deala residues in SIM's are changed to those of the Ile-Ala residue in TST, that (2) SIM-B lacks of the terminal Deala-Deala residue in the long side-chain, and that (3) SIM-C has an unknown amino-acid residue instead of the terminal Deala. On the basis of the above spectral and other chemical studies, and a tentative structure (Ia) proposed for TST by an X-ray crystallographic analysis, the structures Ib, II, and III were concluded to be assigned to TST, and SIM-A and -B, respectively.