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：1981
卷号：78
期号：2
页码：681-685
DOI：10.1073/pnas.78.2.681
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The cyclic hexapeptides (Gly-L-Pro-L-Pro-Gly-L-Pro-L-Pro) in the (peptide--Mg--peptide)2+ complex have nearly identical asymmetric conformations. Each has two cis Pro-Pro linkages and lacks any intraring hydrogen bonds. The Mg2+ ion forms six ligands in a regular octahedral array with the carbonyl oxygen atoms of the two Gly residues and one Pro residue of each peptide. The "sandwich" complex has an approximate 2-fold rotation axis through the Mg2+ relating the two peptide moieties. Cyclo(Gly-Pro-Pro-Gly-Pro-Pro)2Mg(ClO4)2{middle dot} 4C2H3CN crystallizes in space group P31 with a = b = 15.744(4) A, c = 24.002(6) A, {gamma} = 120{degrees
