著者

濱田 季之 松永 茂樹 伏谷 伸宏 藤原 正子 藤田 憲一

出版者

天然有機化合物討論会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

no.37, pp.695-700, 1995-09-01

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A highly cytotoxic polypeptide, polytheonamide B (1), has been isolated from the marine sponge Theonella swinhoei. The structure of polytheonamide B was determined, to be a linear 48-residues polypeptide with the N-terminus blocked by a carbamoyl group, by extensive 2D NMR experiments in DMSO-d_6. The absolute configuration of each amino acid residue was determined by chiral chromatographies of fragment peptides obtained by partial acid hydrolysis of polytheonamide B. Amino acid residues in polytheonamide B have alternating D- and L-configuration. The NMR spectra in CD_3OH/CDCl_3 (1:1) indicated that polytheonamide B adopted certain secondary structure. Conformation analysis was carried out by distance geometry calculations, by DADAS90 program, using NMR parameters obtained in CD_3OH/CDCl_3 (1:1), i.e., a total of 378 distance constraints (160 intra-residue, 96 sequential, 80 long-range NOEs, and 42 hydrogen bonds) and 48 dihedral angle constraints. The calculated structure fit a right-handed parallel β-helix structure, which was proposed for the structure of a pore-forming peptide, gramicidin A.