Search results for "Biophysics"

Incorporation of ATP synthetase into long-term stable liposomes of a polymerizable synthetic sulfolipid

1981

2019

Abstract In high sensitivity inductive electron spin resonance spectroscopy, superconducting microwave resonators with large quality factors are employed. While they enhance the sensitivity, they also distort considerably the shape of the applied rectangular microwave control pulses, which limits the degree of control over the spin ensemble. Here, we employ shaped microwave pulses compensating the signal distortion to drive the spins faster than the resonator bandwidth. This translates into a shorter echo, with enhanced signal-to-noise ratio. The shaped pulses are also useful to minimize the dead-time of our spectrometer, which allows to reduce the wait time between successive drive pulses.

Structure and pair correlations of a simple coarse grained model for supercritical carbon dioxide

2009

A recently introduced coarse-grained pair potential for carbon dioxide molecules is used to compute structural properties in the supercritical region near the critical point, applying Monte Carlo simulations. In this model, molecules are described as point particles, interacting with Lennard-Jones (LJ) forces and a (isotropically averaged) quadrupole–quadrupole potential, the LJ parameters being chosen such that gratifying agreement with the experimental phase diagram near the critical point is obtained. It is shown that the model gives also a reasonable account of the pair correlation function, although in the nearest neighbour shell some systematic discrepancies between the model predicti…

Mechanism of Sinoatrial Node Dysfunction in a RyR 2 R420Q Mouse Model Ofcatecholaminergic Polymorphic Ventricular Tachycardia

2017

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a genetic disease characterized by stress-induced syncope and/or sudden death in young individuals with structurally normal heart. More than 150 mutations located in the cardiac Ca2+ release channel (type-2 ryanodine receptor, RyR2) gene are related to CPVT. Besides ventricular tachycardia (VT) under stress, sinoatrial node (SAN) dysfunction is frequently observed in CPVT patients. However, the cellular mechanisms remain underexplored. We created a KI mice model bearing a mutation in the N-terminal portion of the RyR2 found in a CPVT family, RyR2(R420Q). ECGs were recorded in KI and WT littermates in resting condition and after…

Surface topography of membrane domains

2010

金沢大学理工研究域数物科学系

Deformation of sulfur hexafluoride and floppiness of trifluoromethyl sulfur pentafluoride

2006

International audience; With recent advances in space exploration and atmospheric chemistry there is an increased need for more spectroscopic tools to allow the of study complex species. One such tool is the theory of frame transformation of coupled rotor systems. In this article, the theory of frame transformation along with the concept of rotational energy surface is used to study the symmetry that occurs in trifluoromethyl sulfur pentafluoride due to the internal rotation of the CF3 radical and, more generally, to the extent of floppiness of SF5CF3. Other lower symmetries when a CF4 molecule is stuck on the various symmetry axes of an SF6 molecule are also discussed.

New insight into the aptamer conformation and aptamer/protein interaction by surface-enhanced Raman scattering and multivariate statistical analysis

2021

International audience; We study the interaction between one aptamer and its analyte (the MnSOD protein) by the combination of surface-enhanced Raman scattering and multivariate statistical analysis. We observe the aptamer structure and its evolution during the interaction under different experimental conditions (in air or in buffer). Through the spectral treatment by principal component analysis of a large set of SERS data, we were able to probe the aptamer conformations and orientations relative to the surface assuming that the in-plane nucleoside modes are selectively enhanced. We demonstrate that the aptamer orientation and thus its flexibility rely strongly on the presence of a spacer …

Quantifying the limits of transition state theory in enzymatic catalysis

2017

Significance Transition state theory (TST) is the most popular theory to calculate the rates of enzymatic reactions. However, in some cases TST could fail due to the violation of the nonrecrossing hypothesis at the transition state. In the present work we show that even for one of the most controversial enzymatic reactions—the hydride transfer catalyzed by dihydrofolate reductase—the error associated to TST represents only a minor correction to the reaction rate. Moreover, this error is actually larger for the reaction in solution than in the enzymatic active site. Based on this finding and on previous studies we propose an “enzymatic shielding” hypothesis which encompasses various aspects …

Surface Characteristics Control the Attachment and Functionality of (Chimeric) Avidin

2018

The physical adsorption (physisorption) of proteins to surfaces is an important but incompletely understood factor in many biological processes and is of increasing significance in bionanotechnology as well. Avidin is an important protein because of strong avidin–biotin binding, which has been exploited in numerous applications. We have undertaken thorough experimentation on the physisorption of avidin, to chemically different flat surfaces of Si and graphite and also to the curved version of the latter, on multiwalled carbon nanotubes (MWNTs) of different diameters. The difference in the behavior of avidin on Si versus graphite is drastic; on Si, avidin deposits as single globular tetramer…

Printing Life-Inspired Subcellular Scale Compartments with Autonomous Molecularly Crowded Confinement.

2019

A simple, rapid, and highly controlled platform to prepare life-inspired subcellular scale compartments by inkjet printing has been developed. These compartments consist of fL-scale aqueous droplets (few µm in diameter) incorporating biologically relevant molecular entities with programmed composition and concentration. These droplets are ink-jetted in nL mineral oil drop arrays allowing for lab-on-chip studies by fluorescence microscopy and fluorescence life time imaging. Once formed, fL-droplets are stable for several hours, thus giving the possibility of readily analyze molecular reactions and their kinetics and to verify molecular behavior and intermolecular interactions. Here, this pla…