Spectrofluorimetrie appliquee a de la farine et du gluten de ble tendre pour l'etude des interactions lipide-proteine

illus. 27 ref.International audienc

Triple helix structures: sequence dependence, flexibility and mismatch effects.

International audienceBy means of molecular modelling, electrostatic interactions are shown to play an important role in the sequence-dependent structure of triple helices formed by a homopyrimidine oligonucleotide bound to a homopurine. homopyrimidine sequence on DNA. This is caused by the presence of positive charges due to the protonation of cytosines in the Hoogsteen-bonded strand, required in order to form C.GxC+ triplets. Energetic and conformational characteristics of triple helices with different sequences are analyzed and discussed. The effects of duplex mismatches on the triple helix stability are investigated via thermal dissociation using UV absorption.By means of molecular modelling, electrostatic interactions are shown to play an important role in the sequence-dependent structure of triple helices formed by a homopyrimidine oligonucleotide bound to a homopurine. homopyrimidine sequence on DNA. This is caused by the presence of positive charges due to the protonation of cytosines in the Hoogsteen-bonded strand, required in order to form C.GxC+ triplets. Energetic and conformational characteristics of triple helices with different sequences are analyzed and discussed. The effects of duplex mismatches on the triple helix stability are investigated via thermal dissociation using UV absorption

Application de la fluorescence frontale a l'etude de la conformation des proteines et des interactions lipides-proteines de produits alimentaires au comportement viscoelastique. 2- Cas du gluten

International audienc

Application de la fluorescence frontale a l'etude de la conformation des proteines et des interactions lipides-proteines de produits alimentaires au comportement viscoelastique. 1- Dispositif experimental et validite des mesures de fluorescence frontale

International audienc

Intercalation of ethidium bromide into a triple-stranded oligonucleotide.

We have examined the ability of a cationic planar chromophore, ethidium bromide, to intercalate into a short, defined triple helix. Using UV absorption, fluorescence spectroscopy and a gel retardation assay we demonstrate that ethidium bromide is able to bind to a triple helix with a lower affinity than to the corresponding duplex. Energy transfer from base triplets to ethidium shows that ethidium is intercalated into the triple helix. The spectroscopic characteristics of ethidium intercalated into a triplex are similar to those observed for intercalation into duplex DNA