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Publication Abstract from PubMed

Polytheonamide B (pTB), a highly cytotoxic polypeptide, is one of the most unusual nonribosomal peptides of sponge origin. pTB is a linear 48-residue peptide with alternating d- and l-amino acids and contains a total of eight types of nonproteinogenic amino acids. To investigate the mechanisms underlying its cytotoxic activity, we determined the three-dimensional structure of pTB by NMR spectroscopy, structure calculation, and energy minimization. pTB adopts a single right-handed beta(6.3)-helical structure in a 1:1 mixture of methanol/chloroform with a length of approximately 45 A and a hydrophilic pore of ca. 4 A inner diameter. These features indicate that pTB molecules form transmembrane channels that permeate monovalent cations as gramicidin A channels do. The strong cytotoxicity of pTB can be ascribed to its ability to form single molecule channels through biological membranes.

Solution Structure of Polytheonamide B, a Highly Cytotoxic Nonribosomal Polypeptide from Marine Sponge.,Hamada T, Matsunaga S, Fujiwara M, Fujita K, Hirota H, Schmucki R, Guntert P, Fusetani N J Am Chem Soc. 2010 Aug 26. PMID:20795624^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.