Facile and high yielding syntheses of phosphatidylcholines and phosphatidylethanolamines containing 2 H labeled acyl chains

NRC publication: Ye

NMR and ESR study of the conformations and dynamical properties of poly(L-lysine) in aqueous solutions

International audienceThe conformations and dynamical behavior of poly(L-lysine) (PLL) in aqueous solutions have been investigated by and l8C NMR as well as by ESR on the end-chain spin-labeled polymer. The ESR allowed the motion of the macromolecular chain to be studied up to pH 13, showing that the random coil-*-helix transition at pH 11 gives rise to a twofold increase in the correlation time, with evidence of an anisotropic reorientation. In the random coil state at pH 7, where the segmental motion of the backbone is quasi-isotropic, the correlation time given by ESR is compared to that obtained by the relaxation of the methyl protons of the reduced Tempo radical residue and of the a carbons. The different methods yield an activation energy of 6.5 kcal mol"1 for this motion whereas the frequency dependence of the Ca relaxation may be interpreted by a Cole-Cole distribution of correlation times with a width parameter = 0.7. The rotational isomerism and temperature dependences of interconversion rates of the aminobutyl side chains have been analyzed from the proton vicinal couplings and the 13C and relaxation at different frequencies, assuming that the methylene groups undergo 120°j umps among three sites, two of them being equiprobable. These two kinds of information concur to show that the PLL side chains are less flexible than a hydrocarbon chain of same length, possibly because of the hydration of the NH3+ terminal group

Self assemblies of amphiphilic cyclodextrins

International audienc

Acyl chain dynamics of phosphatidylethanolamines containing oleic acid and dihydrosterculic acid: 2 H-NMR relaxation studies: Biochemistry

NRC publication: Ye

Effects of the replacement of a double bond by a cyclopropane ring in phosphatidylethanolamines: A 2 H-NMR study of phase transitions and molecular organization: Biochemistry

NRC publication: Ye

Étude par RMN de la reconnaissance chirale par des cyclodextrines modifiées

Le mono-3A, 6A-anhydro-cyclomaltohcptaose est un analogue de la β-cyclodextrine présentant une réduction totale de symétrie induisant des propriétés de reconnaissance chirale remarquables. Une étude structurale par RMN a été effectuée sur un complexe d’inclusion formé avec un atropo-isomère, la dothiépine. Cette étude a montré que chaque énantiomère forme un complexe d’inclusion de structure et d’affinité différentes