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Preparation and NMR Structure of the Cyclo‐ β ‐tripeptide [ β 3 ‐HGlu] 3 in Aqueous Solution: A New Class of Enterobactin‐Type C 3 ‐Symmetrical Ligands?, Preliminary Communication
Author(s) -
Gademann Karl,
Seebach Dieter
Publication year - 1999
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/(sici)1522-2675(19990609)82:6<957::aid-hlca957>3.0.co;2-h
Subject(s) - chemistry , tripeptide , enterobactin , ring (chemistry) , stereochemistry , nuclear magnetic resonance spectroscopy , aqueous solution , proton nmr , crystallography , combinatorial chemistry , peptide , organic chemistry , siderophore , biochemistry , gene
To date, cyclo‐ β ‐tripeptides (twelve‐membered‐ring trilactams, C ) have resisted structural investigations because of their extreme insolubility. Modelling and comparison with the corresponding tetramers indicate that the rings stack to form tube‐like hydrogen‐bonded aggregates ( D ). By exploiting the solubilizing effect of LiCl on peptides in THF, we were able to prepare the water‐soluble title compound and determine its structure ( E ) by NMR spectroscopy. Structural similarities and differences between the trilactam ring of [ β 3 ‐HGlu] 3 and the corresponding trilactone ring, such as that of enterobactin ( A ), are discussed, and structures (`elongated'; F , G ) are proposed that should be able to serve as tridentate or trivalent ligands for metal centers.