Probing helix propensity of monomers within a helical oligomer. - Université Pierre et Marie Curie Accéder directement au contenu
Article Dans Une Revue Proceedings of the National Academy of Sciences of the United States of America Année : 2005

Probing helix propensity of monomers within a helical oligomer.

Résumé

A simple strategy is proposed to assess the propensity of a given monomer to follow or not follow a particular helical scheme and to study helix reversal phenomena within helical oligomers. It consists of placing a monomer having a low helix propensity between two conformationally stable helical segments. Helix reversion then occurs preferentially at the site of this monomer, leading to the formation of isomers having P (right-handed) or M (left-handed) helicities at each of the two helical segments. The proportion between the P-P/M-M and P-M isomers is indicative of the stereochemical relations between the inserted monomer and the helical frame. Thus, xylylene or carboxylic acid anhydride spacers have been introduced between two helical oligoamides of 8-amino-2-quinolinecarboxylic acid. Both these spacers presumably lack some of the structural features that confer quinoline units with a high helix propensity. Only one species is observed in solution in the case of an anhydride spacer. This species was shown by x-ray crystallography to be a racemic mixture of P-P and M-M helices. Unexpectedly, the anhydride is consistently incorporated within helical oligoamides. For the xylylene spacer, the P-P/M-M racemate and P-M meso compound are in equal proportions in chloroform, showing that this spacer does not have a propensity to adopt any helical conformation in this solvent. However, the equilibria between the various isomers are shifted in toluene, where one species largely prevails. This species was shown by x-ray crystallography to be the P-P/M-M racemate. Molecular dynamics simulations are consistent with these solution data.

Domaines

Chimie organique

Dates et versions

hal-00734000 , version 1 (20-09-2012)

Identifiants

Citer

Christel Dolain, Jean-Michel Léger, Nicolas Delsuc, Heinz Gornitzka, Ivan Huc. Probing helix propensity of monomers within a helical oligomer.. Proceedings of the National Academy of Sciences of the United States of America, 2005, 102 ((45)), pp.16146-51. ⟨10.1073/pnas.0506262102⟩. ⟨hal-00734000⟩
35 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More