Search results for "CIRCULAR-DICHROISM"
showing 9 items of 9 documents
[Au(9-methylcaffein-8-ylidene) 2 ] + /DNA Tel23 System: Solution, Computational, and Biological Studies
2017
International audience; Physicochemical methods have been used to investigate interactions occurring in solution between the dicarbene gold(I) complex [Au(9‐methylcaffein‐8‐ylidene)2]BF4 (AuNHC) and a human telomeric DNA sequence, namely Tel23. Circular dichroism measurements allow identification of the conformational changes experienced by Tel23 upon interaction with AuNHC, and the respective binding stoichiometries and constants were determined. Computational studies provide a good link between previous crystallographic results of the same system and the present solution data, offering an exhaustive description of the inherent noncovalent metallodrug–DNA interactions. Remarkably, we found…
Aza-macrocyclic triphenylamine ligands for G-quadruplex recognition
2018
A new series of triphenylamine-based ligands with one (TPA1PY), two (TPA2PY) or three pendant aza-macrocycle(s) (TPA3PY) has been synthesised and studied by means of pH-metric titrations, UV/Vis spectroscopy and fluorescence experiments. The affinity of these ligands for G-quadruplex (G4) DNA and the selectivity they show for G4s over duplex DNA were investigated by Forster resonance energy transfer (FRET) melting assays, fluorimetric titrations and circular dichroism spectroscopy. Interestingly, the interactions of the bi- and especially the tri-branched ligands with G4s lead to a very intense redshifted fluorescence emission band that may be associated with intermolecular aggregation betw…
Direct observation of alpha-lactalbumin, adsorption and incorporation into lipid membrane and formation of lipid/protein hybrid structures
2019
The interaction between proteins and membranes is of great interest in biomedical and biotechnological research for its implication in many functional and dysfunctional processes. We present an experimental study on the interaction between model membranes and alpha-lactalbumin (alpha-La). alpha-La is widely studied for both its biological function and its anti-tumoral properties. We use advanced fluorescence microscopy and spectroscopy techniques to characterize alpha-La-membrane mechanisms of interaction and alpha-La-induced modifications of membranes when insertion of partially disordered regions of protein chains in the lipid bilayer is favored. Moreover, using fluorescence lifetime imag…
Interaction of Cd(II) and Ni(II) terpyridine complexes with model polynucleotides: A multidisciplinary approach
2016
Two metal complexes of 2,2′:6′,2′′-terpyridine (terpy), i.e. Cd(terpy)Cl2 and Ni(terpy)Cl2·3H2O, have been prepared and extensively characterized. The interaction of Cd(terpy)Cl2 with synthetic DNA models, poly(dA-dT)·poly(dA-dT) (polyAT) and poly(dG-dC)·poly(dG-dC) (polyGC), has been studied by CD, fluorescence and UV-vis electronic absorption spectroscopy at several metal/polynucleotide–phosphate ratios and for different NaCl concentrations. All the experimental results indicate an intercalative mechanism of interaction. The optimized geometry of the cadmium complex intercalated between the sixth and seventh base pairs of (AT) and (GC) dodecanucleotide duplexes, obtained by quantum mechan…
Carboxylated-xyloglucan and peptide amphiphile co-assembly in wound healing.
2021
Abstract Hydrogel wound dressings can play critical roles in wound healing protecting the wound from trauma or contamination and providing an ideal environment to support the growth of endogenous cells and promote wound closure. This work presents a self-assembling hydrogel dressing that can assist the wound repair process mimicking the hierarchical structure of skin extracellular matrix. To this aim, the co-assembly behaviour of a carboxylated variant of xyloglucan (CXG) with a peptide amphiphile (PA-H3) has been investigated to generate hierarchical constructs with tuneable molecular composition, structure, and properties. Transmission electron microscopy and circular dichroism at a low c…
Exchange coupling in the correlated electronic states of amorphous GdFe films
2013
The bulk sensitivity of hard x-ray photoelectron spectroscopy in combination with circularly polarized radiation of the P09 beamline at PETRA III enables the investigation of the magnetic properties of capped films. We have determined the temperature dependence of the magnetic circular dichroism in the Fe 2$p$ and in the Gd 3$d$ states in amorphous GdFe films. The magnetic dichroism reflects the stronger temperature dependence of Gd moments compared to Fe moments in agreement with mean-field models. We resolved the exchange split Gd 3${d}_{5/2}$ substates and found a significant temperature dependence of the splitting which is attributed to a temperature dependent part of the exchange energ…
Regional Susceptibility in VCD Spectra to Dynamic Molecular Motions
2018
Experimental and theoretical studies of the vibrational circular dichroism (VCD) spectrum of 3-methyl-1-(methyldiphenlsilyl)-1-phenylbutan-1-ol, whose absolute configuration is key to elucidating the Brook rearrangement of tertiary benzylic α-hydroxylsilanes, are presented. It is found that the entire OH-bending region in this spectrum—a region that provides important marker bands—cannot be reproduced at all by standard theoretical approaches even though other regions are well described. Using a novel approach to disentangle contributions to the rotational strength of these bands, internal coordinates are identified that critically influence the appearance of this part of the spectrum. We s…
Optical rotary power at the resonance of the terbium F-7(6)-> D-5(4) line in terbium gallium garnet
1998
0038-1101; The Tb3+ absorption line F-7(6)-->D-5(4) Of the Terbium Gallium Garnet crystal is excited with an Argon ion laser. The Verdet's constant has been determined and reported against 1/lambda(2), showing no significant resonant behaviour at absorption resonance. The utility and the constraints of the crystal at this particular resonant wavelength are pointed out. (C) 1998 Elsevier Science Ltd. All rights reserved.
PLA2-mediated catalytic activation of its inhibitor 25-acetyl-petrosaspongiolide M: serendipitous identification of a new PLA2 suicide inhibitor.
2004
Abstract25-Acetyl-petrosaspongiolide M (PMAc) (1), a mild non-covalent PLA2 inhibitor, unexpectedly recovers, after incubation with bvPLA2, the ability to covalently modify the enzyme target. This study demonstrates the catalytic effect of bvPLA2 in converting 1 in its deacetylated congener petrosaspongiolide M (PM) (2), a strong covalent PLA2 inhibitor whose molecular mechanism of inhibition has already been clarified. Moreover, our findings outline the potential role of PMAc as anti-inflammatory pro-drug, by virtue of its ability of delivering the active PM agent at the site of inflammation, functioning as a suicide inhibitor.