Search results for "circular"
showing 10 items of 856 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…
Structure and Stability of Hsp60 and Groel in Solution
2016
Molecular chaperones are a class of proteins able to prevent non-specific aggregation of mitochondrial proteins and to promote their proper folding. Among them, human Hsp60 is currently considered as a ubiquitous molecule with multiple roles both in maintaining health conditions and as a trigger of several diseases. Of particular interest is its role in neurodegenerative disorders since it is able to inhibit the formation of amyloid fibrils.Hsp60 structure was considered, until recent years, analogue to the one of its bacterial homolog GroEL, one of the most investigated chaperones, whose crystallographic structure is a homo-tetradecamer, made up of two seven member rings. On the contrary, …
Specific and highly efficient condensation of GC and IC DNA by polyaza pyridinophane derivatives
2018
Abstract Two bis-polyaza pyridinophane derivatives and their monomeric reference compounds revealed strong interactions with ds-DNA and RNA. The bis-derivatives show a specific condensation of GC- and IC-DNA, which is almost two orders of magnitude more efficient than the well-known condensation agent spermine. The type of condensed DNA was identified as ψ-DNA, characterized by the exceptionally strong CD signals. At variance to the almost silent AT(U) polynucleotides, these strong CD signals allow the determination of GC-condensates at nanomolar nucleobase concentrations. Detailed thermodynamic characterisation by ITC reveals significant differences between the DNA binding of the bis-deriv…
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…
Biophysical and functional characterization of the human olfactory receptor OR1A1 expressed in a mammalian inducible cell line
2014
International audience; Olfactory receptors (ORs) play a crucial role in detecting the odorant molecules present in the surrounding environment. These receptors, which belong to class A G-protein-coupled receptors, constitute the largest transmembrane protein family in the human genome. Functional studies showed that the OR family includes members that are able to respond to a large set of odorants and members that are activated by a relatively small number of related odorants. To understand the molecular mechanisms that govern the receptor-ligand interactions, we overexpressed the human OR hOR1A1 in a stable tetracycline-inducible HEK293S cell line. This receptor was engineered by insertin…
Effect of high pressure on the antimicrobial activity and secondary structure of the bacteriocin nisin
2018
International audience; Effect of high pressure (HP) treatment on the antimicrobial properties and the structure of nisin was evaluated. Nisin solutions at pH 2.8 or 6.1 were treated by HP at 500 MPa – 10 min – 20 °C and their antimicrobial potency was determined. It appeared that HP clearly impacted the antimicrobial activity of nisin, with respective activity loss of 22.5% and 49.9% at pH 2.8 and 6.1. Structural analysis of nisin by circular dichroism and Fourier transform-infrared spectroscopies revealed that the decrease of nisin antimicrobial activity was likely due to the unfolding of the protein induced by HP. A loss of nisin β-turns structure, particularly significant at neutral pH,…
The Potential of Serum Exosomal hsa_circ_0028861 as the Novel Diagnostic Biomarker of HBV-Derived Hepatocellular Cancer
2021
Hepatitis B virus (HBV)-derived hepatocellular cancer (HCC) is a serious threat to human health, especially in China. There is no highly sensitive and specific HCC biomarker at present, which makes it difficult to detect HCC at the early stage. Serum exosomal circular RNAs (circRNAs) have been reported as novel diagnostic and prognostic biomarkers of cancers. In the present study, we aimed to explore the diagnostic performance of serum exosomal circRNAs for HBV-derived HCC screening. At first, many circRNAs were found to be differentially expressed in the serum exosomes of HCC individuals by microarray analysis. The validation of dysregulated circRNAs by qRT-PCR revealed that serum exosomal…
Alignment-free sequence comparison using absent words
2018
Sequence comparison is a prerequisite to virtually all comparative genomic analyses. It is often realised by sequence alignment techniques, which are computationally expensive. This has led to increased research into alignment-free techniques, which are based on measures referring to the composition of sequences in terms of their constituent patterns. These measures, such as $q$-gram distance, are usually computed in time linear with respect to the length of the sequences. In this paper, we focus on the complementary idea: how two sequences can be efficiently compared based on information that does not occur in the sequences. A word is an {\em absent word} of some sequence if it does not oc…
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…
Genetic Diversity of O-Antigens in Hafnia alvei and the Development of a Suspension Array for Serotype Detection.
2016
Hafnia alvei is a facultative and rod-shaped gram-negative bacterium that belongs to the Enterobacteriaceae family. Although it has been more than 50 years since the genus was identified, very little is known about variations among Hafnia species. Diversity in O-antigens (O-polysaccharide, OPS) is thought to be a major factor in bacterial adaptation to different hosts and situations and variability in the environment. Antigenic variation is also an important factor in pathogenicity that has been used to define clones within a number of species. The genes that are required to synthesize OPS are always clustered within the bacterial chromosome. A serotyping scheme including 39 O-serotypes has…