ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
CD and nmr techniques have been used to study, in acetonitrile solution, the ion-complexing capability of Cyclolinopeptide A (CLA), a cyclic nonapeptide of sequence \documentclass{article}\pagestyle{empty}\begin{document}$$ cyclo{\rm - }\left({{\rm Pro - Pro - Phe - Phe - Leu - Ile - Ile - Leu - Val}} \right) $$\end{document} endowed with remarkable cytoprotective ability in vitro, and the conformation of the Ba2+/ CLA complex.At room temperature, CLA in acetonitrile shows a proton nmr spectrum characteristic of the coexistence of many different conformers in intermediate exchange. The backbone contains a cis Pro-Pro bond, with all other peptide bonds in the transconformation.CLA binds Ba2+ more tightly than the other cations studied, namely K+, Na+, Mg2+, and Ca2+; CD data are indicative of the presence of both 1 : 2 (sandwich) and 1 : 1 (equimolar) type complexes, depending on the Ba2+ ion concentration, whereas nmr data are consistent with an equimolar form.The relevant conformational features of the equimolar Ba2+/CLA complex are that the backbone contains all transpeptide bonds, a type I 6 → 3 β-turn and a 3 → 1 γ-turn (or a distorted 3 → 9 β-turn). The global shape of the complexed peptide can be described as a bowl, with the concave (polar) side hosting Ba2+ and the convex side predominantly apolar.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.360310621
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