期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1973
卷号：70
期号：6
页码：1836-1840
DOI：10.1073/pnas.70.6.1836
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Antamanide, a cyclic decapeptide isolated from the poisonous mushroom Amanita phalloides, preferably complexes with Na+, but in less polar solvents, e.g., acetonitrile, also with Li+ or K+. The selectivity of complexation makes it an important model for the study of conformational requirements of ion binding. The conformations of the lithium antamanide complex and the Na-[Phe4, Val6]antamanide complex have been established by x-ray diffraction analyses of single crystals. The two compounds are isostructural, but not isomorphous. The complexes are folded into a globular shape with an approximate 2-fold axis. Two of the peptide linkages are in the cis conformation, Pro2-Pro3 and Pro7-Pro8. There are only two intramolecular hydrogen bonds. Four C==O groups have their O atoms directed inward to form four Li-O or Na-O ligands. The fifth ligand to the metal ion is provided by a solvent molecule. The conformation found in the crystalline state is different from any of the conformations proposed for the sodium antamanide complex in solution on the basis of nuclear magnetic resonance data.
关键词：Roentgen-ray analysis ; cyclic peptides ; cis - and trans -peptide bonds ; penta-coordinate sodium and lithium complexes ; ion transport
