Search results for "Biomolecule"

Physico-chimie des lipopolysaccharides et réponse inflammatoire : rôle des lipoprotéines

2014

LPS is a potent bacterial pro-inflammatory agent, consisting of hydrophilic, polysaccharide part and of a lipid A which is considered like active moiety. Nevertheless, the O chain of LPS influences their aggregation in aqueous media. Therefore, our goal has been to determine the role of O chain on the LPS biological and physiopathological effects. Our work was organized according to three main axes, and led to the following findings :- development of a new LPS assay by LC-MS/MS. The combination of this new technique with LAL test allowed us to calculate an inactivation ratio which reflects the ability of host organism to inactivate LPS, especially through their transfer to HDL by PLTP. The …

Corrigendum: Organometallic complexes with biological molecules: VII. Diorgano- and triorgano-tin(IV)[meso-tetra(4-carboxyphenyl)porphinate] derivati…

1997

Organometallic complexes with biological molecules. XIV. Biological activity of dialkyl and trialkyltin(IV) [meso-tetra(4-carboxy- phenyl)porphinate]…

2000

Molecules. XIV. Biological Activity of Dialkyl and Trialkyltin(IV) [Meso-tetra(4-carboxyphenyl)porphinate] Derivatives C. Mansueto, E. Puccia, F. Maggio, R. Di Stefano, T. Fiore, C. Pellerito, F. Triolo and L. Pellerito* Dipartimento di Biologia Animale, Universita di Palermo, Via Archirafi 18, 90123 Palermo, Italy Dipartimento di Chimica Inorganica, Universita di Palermo, Viale delle Scienze, Parco d’Orleans, 90128 Palermo, Italy

Myoglobin on Silica: A Case Study of the Impact of Adsorption on Protein Structure and Dynamics

2013

International audience; If protein structure and function changes upon adsorption are well documented, modification of adsorbed protein dynamics remains a blind spot, despite its importance in biological processes. The adsorption of metmyoglobin on a silica surface was studied by isotherm measurements, microcalorimetry, circular dichroïsm, and UV-visible spectroscopy to determine the thermodynamic parameters of protein adsorption and consequent structure modifications. The mean square displacement and the vibrational densities of states of the adsorbed protein were measured by elastic and inelastic neutron scattering experiments. A decrease of protein flexibility and depletion in low freque…

Frictional Forces between Strongly Compressed, Nonentangled Polymer Brushes: Molecular Dynamics Simulations and Scaling Theory

2010

By means of molecular dynamics simulations and scaling theory we study the response of opposing polymer brushes to constant shear motion under good solvent conditions. Model systems that contain explicit solvent molecules (Lennard-Jones dimers) are compared to solvent-free systems while varying of the distance between the grafted layers and their molecular parameters, chain length and grafting density. Our study reveals a power-law dependence of macroscopic transport properties on the Weissenberg number, W, beyond linear response. For instance, we find that the kinetic friction constant scales as μ ∼ W0.57 for large values of W. We develop a scaling theory that describes our data and previo…

Suitability of Phytosterols Alongside Fatty Acids as Chemotaxonomic Biomarkers for Phytoplankton

2016

The composition and abundance of phytoplankton is an important factor defining ecological status of marine and freshwater ecosystems. Chemotaxonomic markers (e.g., pigments and fatty acids) are needed for monitoring changes in a phytoplankton community and to know the nutritional quality of seston for herbivorous zooplankton. Here we investigated the suitability of sterols along with fatty acids as chemotaxonomic markers using multivariate statistics, by analyzing the sterol and fatty acid composition of 10 different phytoplankton classes including altogether 37 strains isolated from freshwater lakes. We were able to detect a total of 47 fatty acids and 29 sterols in our phytoplankton sampl…

"Table 1" of "J/psi polarization in pp collisions at sqrt(s)=7 TeV"

2016

$\lambda_\theta$ as a function of $p_{\rm T}$ for inclusive J/$\psi$, measured in the helicity reference frame.

Statistical Thermodynamics of Polymer Quantum Systems

2011

Polymer quantum systems are mechanical models quantized similarly as loop quantum gravity. It is actually in quantizing gravity that the polymer term holds proper as the quantum geometry excitations yield a reminiscent of a polymer material. In such an approach both non-singular cosmological models and a microscopic basis for the entropy of some black holes have arisen. Also important physical questions for these systems involve thermodynamics. With this motivation, in this work, we study the statistical thermody- namics of two one dimensional polymer quantum systems: an ensemble of oscillators that describe a solid and a bunch of non-interacting particles in a box, which thus form an ideal…

Intramolecular phase separation of copolymer "bottle brushes": No sharp phase transition but a tunable length scale

2006

A lattice model for a symmetrical copolymer "bottle brush" molecule, where two types (A,B) of flexible side chains are grafted with one chain end to a rigid backbone, is studied by a variant of the pruned-enriched Rosenbluth method (PERM), allowing for simultaneous growth of all side chains in the Monte Carlo sampling. Choosing repulsive binary interactions between unlike monomers and varying the solvent quality, it is found that phase separation into an $A$-rich part of the cylindrical molecule and a $B$-rich part can occur only locally. Long range order (in the direction of the backbone) does not occur, and hence the transition from the randomly mixed state of the bottle brush to the phas…

Can Soft Models Describe Polymer Knots?

2020

Similar to macroscopic ropes and cables, long polymers create knots. We address the fundamental question whether and under which conditions it is possible to describe these intriguing objects with crude models that capture only mesoscale polymer properties. We focus on melts of long polymers which we describe by a model typical for mesoscopic simulations. A worm-like chain model defines the polymer architecture. To describe nonbonded interactions, we deliberately choose a generic "soft" repulsive potential that leads to strongly overlapping monomers and coarse local liquid structure. The soft model is parametrized to accurately reproduce mesoscopic structure and conformations of reference p…