Search results for "molecule"

Single-Molecule Magnets: Electrostatic Anchoring of Mn4 Single-Molecule Magnets onto Chemically Modified Multiwalled Carbon Nanotubes (Adv. Funct. Ma…

2012

EVpedia: a community web portal for extracellular vesicles research

2014

Abstract Motivation: Extracellular vesicles (EVs) are spherical bilayered proteolipids, harboring various bioactive molecules. Due to the complexity of the vesicular nomenclatures and components, online searches for EV-related publications and vesicular components are currently challenging. Results: We present an improved version of EVpedia, a public database for EVs research. This community web portal contains a database of publications and vesicular components, identification of orthologous vesicular components, bioinformatic tools and a personalized function. EVpedia includes 6879 publications, 172 080 vesicular components from 263 high-throughput datasets, and has been accessed more tha…

Synthesis of calcium carbonate biological materials: how many proteins are needed?

2013

In Nature, calcium carbonate biomineralizations are the most abundant mineralized structures of biological origin. Because many exhibit remarkable characteristics, several attempts have been made to use them as substitution materials for bone reconstruction or as models for generating biomimetic composites that exhibit tailored properties. CaCO3biomineralizations contain small amounts of amalgamate of proteins and polysaccharides that are secreted during the calcification process. They contribute to control the morphology of the crystallites and to spatially organize them in well-defined microstructures. These macromolecules, collectively defined as the skeletal matrix, have been the focus …

Production, fonction et localisation d'Orchestine: calciprotéine spécifique de la matrice organique des structures minéralisées élaborées par le crus…

2002

As most Crustaceans, Orchestia cavimana possesses a mineralized exoskeleton which is periodically replaced. Because of the terrestrial behaviours of this animal, this molting cycle is related to calcium storage and resorption processes. Calcium storage occurs, as calcareous concretions, in diverticula of the midgut called posterior cæca. Calcareous concretions are essentially composed of amorphous calcium carbonate precipitated within a proteinaceous organic matrix composed of a soluble fraction and an insoluble one in an EDTA-buffer. Among the soluble components of the organic matrix, a previous study led to characterize a polypeptide of 23 kDa in SDS-PAGE called Orchestin. This protein, w…

A photoswitchable helical peptide with light-controllable interface/transmembrane topology in lipidic membranes

2021

Summary The spontaneous insertion of helical transmembrane (TM) polypeptides into lipid bilayers is driven by three sequential equilibria: solution-to-membrane interface (MI) partition, unstructured-to-helical folding, and MI-to-TM helix insertion. A bottleneck for understanding these three steps is the lack of experimental approaches to perturb membrane-bound hydrophobic polypeptides out of equilibrium rapidly and reversibly. Here, we report on a 24-residues-long hydrophobic α-helical polypeptide, covalently coupled to an azobenzene photoswitch (KCALP-azo), which displays a light-controllable TM/MI equilibrium in hydrated lipid bilayers. FTIR spectroscopy reveals that trans KCALP-azo folds…

Pulsed electric fields (PEF), pressurized liquid extraction (PLE) and combined PEF + PLE process evaluation: Effects on Spirulina microstructure, bio…

2022

This study aims at evaluating the impact of different processes-pulsed electric fields (PEF), pressurized liquid extraction (PLE) and a multistep process combining PEF + PLE on the yield of antioxidant compounds (protein, polyphenols, chlorophyll a, chlorophyll b, and carotenoids) from Spirulina. Firstly, the effects of PEF or PLE treatment on the extraction yield of Spirulina biomolecules were evaluated. To further increase the extraction yield, PEF + PLE was used, as an innovative extraction approach. The results showed that PEF + PLE greatly improved the extraction yield compared with the PEF or PLE treatments alone. Compared with Folch extraction (conventional control technique), PEF + …

Biomolecules and nanostructured systems : characterization by Surface Enhanced Raman Scattering (SERS)

2014

This work addressed the study of several kinds of nanostructured systems, biomolecules and inorganic thin films, mainly by Surface Enhanced Raman Spectroscopy (SERS). The aim was to investigate the structure and the chemical bonds. Transmission electron microscopy (TEM) was also used to complete the structural characterization of the different samples.Firstly, the study was conducted on molecules of biological interest. The aim was to study the interaction between silver nanoparticles and proteins. With this aim, silver nanoparticles bioconjugated with different proteins (hemoglobin, cytochrome C, BSA and lysozim) were synthesized. SERS results allowed concluding that proteins are chemisorb…

Design and computer simulations of 2D MeX2 solid-state nanopores for DNA and protein detection analysis

2020

Solid-state nanopores (SSN) have emerged as versatile devices for biomolecule analysis. One of the most promising applications of SSN is DNA and protein sequencing, at a low cost and faster than the current standard methods. SSN sequencing is based on the measurement of ionic current variations when a biomolecule embedded in electrolyte is driven through a nanopore under an applied electric potential. As a biomolecule translocates through the nanopore, it occupies the pore volume and blocks the passage of ions. Hence, ultrafast monitoring of ionic flow during the passage of a biomolecule yields information about its structure and chemical properties. The size of the sensing region in SSN is…

An ab initio potential energy surface for the C2H2-N2 system

2012

International audience; An ab initio potential energy surface determined at the CCSD(T) level of theory is presented for the van der Waals complex C2H2-N2. Additional calculations performed with the HF- and DFT-SAPT methods compare well with the CCSD(T) results and allow a better understanding of the main features of this interaction potential surface. An expansion of this surface over spherical harmonics has also been performed. The global energy minimum of the complex is obtained for the linear conformation. The T conformations are the least attractive. Such characteristics mainly arise because of the variation, in sign and in absolute value of the electrostatic energy between all these c…

Role of calcium in E-selectin induced phenotype of T84 colon carcinoma cells

2003

The adhesion of cancer cells to the endothelium during the metastatic process involves the interaction of specific cell-cell adhesion receptors on the cell surface. E-selectin on endothelial cells and sialyl Lewis X carbohydrate component on tumor cells are mainly implicated in the adhesion of colon carcinoma cells to the endothelium of target organ. In this paper we show that binding of E-selectin to T84 colon tumor cells causes approximately a twofold increase in intracellular calcium concentration. In particular, using two inhibitors of receptor operated calcium channels, CAI and SK&F 96365, we present evidences that the augmentation in cytoplasmic calcium originates from ionic influx fr…