scholarly journals Monitoring Unfolding of Titin I27 single- and bi-Domain with High-Pressure NMR Spectroscopy

2018 ◽  
Author(s):  
I. Herrada ◽  
P. Barthe ◽  
M. Van Heusden ◽  
K DeGuillen ◽  
L Mammri ◽  
...  
Keyword(s):  
High Pressure ◽  
Force Spectroscopy ◽  
Md Simulations ◽  
Specific Information ◽  
Folding Energy ◽  
3D Scaffold ◽  
Folding Process ◽  
Energetic Characterization ◽  
Volume Kinetics

ABSTRACTA complete description of the pathways and mechanisms of protein folding requires a detailed structural and energetic characterization of the folding energy landscape. Simulations, when corroborated by experimental data yielding global information on the folding process, can provide this level of insight. Molecular Dynamics (MD) has been associated often to force spectroscopy experiments to decipher the unfolding mechanism of titin Ig-like single- or multi-domain, the giant multi-modular protein from sarcomere, yielding information on the sequential events during titin unfolding under stretching. Here, we used high-pressure NMR to monitor the unfolding of titin I27 Ig-like single-domain and tandem. Since this method brings residue-specific information on the folding process, it can provide quasi-atomic details on this process, without the help of MD simulations. Globally, the results of our high-pressure analysis are in agreement with previous results obtained by the association of experimental measurements and MD simulation and/or protein engineering, although the intermediate folding state caused by the early detachment of the AB ß-sheet, often reported in previous works based on MD or force spectroscopy, cannot be detected. On the other hand, the A’G parallel ß-sheet of the ß-sandwich has been confirmed as the Achilles heel of the 3D scaffold: its disruption yields complete unfolding, with very similar characteristics (free energy, unfolding volume, kinetics constant rates) for the two constructs.

scholarly journals Combining High-Pressure Perturbation with NMR Spectroscopy for a Structural and Dynamical Characterization of Protein Folding Pathways

Molecules ◽  
2020 ◽  
Vol 25 (23) ◽  
pp. 5551
Author(s):  
Cécile Dubois ◽  
Isaline Herrada ◽  
Philippe Barthe ◽  
Christian Roumestand
Keyword(s):  
High Pressure ◽  
Protein Folding ◽  
Nmr Spectroscopy ◽  
Protein Structures ◽  
Kinetic Properties ◽  
Folding Energy ◽  
Folding Pathways ◽  
Nmr Techniques ◽  
Protein Folding Pathways

High-hydrostatic pressure is an alternative perturbation method that can be used to destabilize globular proteins. Generally perfectly reversible, pressure exerts local effects on regions or domains of a protein containing internal voids, contrary to heat or chemical denaturant that destabilize protein structures uniformly. When combined with NMR spectroscopy, high pressure (HP) allows one to monitor at a residue-level resolution the structural transitions occurring upon unfolding and to determine the kinetic properties of the process. The use of HP-NMR has long been hampered by technical difficulties. Owing to the recent development of commercially available high-pressure sample cells, HP-NMR experiments can now be routinely performed. This review summarizes recent advances of HP-NMR techniques for the characterization at a quasi-atomic resolution of the protein folding energy landscape.

Deconstructing the Behavior of Donor-Acceptor Copolymers in Solution & the Melt: The Case of PTB7

2019 ◽  
Author(s):  
Sean M. Ryno ◽  
Chad Risko
Keyword(s):  
Solid State ◽  
Organic Semiconductors ◽  
Organic Solar Cell ◽  
Md Simulations ◽  
Specific Information ◽  
Conjugated Molecules ◽  
Electronic Response ◽  
Donor Acceptor ◽  
Detailed Picture

For organic semiconductors, the solid-state packings of the π-conjugated molecules or polymers dictate the material electronic, optical, and mechanical characteristics. Combinations of solution and solid-state investigations are often used to establish structure–function relationships, though these connections are often loosely correlated, and experiments in different laboratories can lead to widely variable interpretations. Hence, there remains a need to develop a deeper, more robust understanding of the connections between molecular and polymer chemistry, structure, processing, solid-state order, and materials properties to enable judicious materials design principles. Towards this goal, we employ fully-atomistic molecular dynamics (MD) simulations of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b’]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)] (PTB7), a donor–acceptor copolymer that has been widely investigated in the organic solar cell literature, to unravel some of these associations. The MD simulations make use of polymer lengths (masses) and solution concentrations that are consistent with those used in experiment, allowing for a detailed picture to arise as to how variations in the polymer environment can direct polymer structure. Comparisons between experiment and theory suggest that processing history can be an important factor in the polymer structures presumed experimentally that are used to interpret optical and electronic response. The results of these simulations provide specific information into the behavior of PTB7 under different conditions, and showcase how atomistic MD simulations that approach experimentally relevant sizes can be used to develop broader chemical insight that can aid in the design, processing, and characterization of polymer-based organic semiconductors.

Deconstructing the Behavior of Donor-Acceptor Copolymers in Solution & the Melt: The Case of PTB7

2019 ◽  
Author(s):  
Sean M. Ryno ◽  
Chad Risko
Keyword(s):  
Solid State ◽  
Organic Semiconductors ◽  
Organic Solar Cell ◽  
Md Simulations ◽  
Specific Information ◽  
Conjugated Molecules ◽  
Electronic Response ◽  
Donor Acceptor ◽  
Detailed Picture

For organic semiconductors, the solid-state packings of the π-conjugated molecules or polymers dictate the material electronic, optical, and mechanical characteristics. Combinations of solution and solid-state investigations are often used to establish structure–function relationships, though these connections are often loosely correlated, and experiments in different laboratories can lead to widely variable interpretations. Hence, there remains a need to develop a deeper, more robust understanding of the connections between molecular and polymer chemistry, structure, processing, solid-state order, and materials properties to enable judicious materials design principles. Towards this goal, we employ fully-atomistic molecular dynamics (MD) simulations of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b’]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)] (PTB7), a donor–acceptor copolymer that has been widely investigated in the organic solar cell literature, to unravel some of these associations. The MD simulations make use of polymer lengths (masses) and solution concentrations that are consistent with those used in experiment, allowing for a detailed picture to arise as to how variations in the polymer environment can direct polymer structure. Comparisons between experiment and theory suggest that processing history can be an important factor in the polymer structures presumed experimentally that are used to interpret optical and electronic response. The results of these simulations provide specific information into the behavior of PTB7 under different conditions, and showcase how atomistic MD simulations that approach experimentally relevant sizes can be used to develop broader chemical insight that can aid in the design, processing, and characterization of polymer-based organic semiconductors.

Separation and Characterization of Standard Propoxyphene Diastereomers and Their Determination in Pharmaceutical and Illicit Preparations

1981 ◽  
Vol 64 (4) ◽  
pp. 875-883
Author(s):  
Shiv K Soni ◽  
Daniel Van Gelder
Keyword(s):  
High Pressure ◽  
Optical Isomers ◽  
Gold Chloride ◽  
Melting Points ◽  
Eutectic Melting ◽  
Racemic Mixtures ◽  
The Individual ◽  
Isomeric Mixtures ◽  
Asymmetric Carbon

Abstract Due to the existence of 2 asymmetric carbon atoms in: the propoxyphene molecule, there are 4 diastereomers: alpha dextro, alpha levo, beta dextro, and beta levo. Only α-d-propoxyphene is included under the federal Controlled Substances Act. Baseline separations of propoxyphene from various incipients (aspirin, caffeine, phenacetin, and acetaminophen) present in pharmaceutical and illicit preparations, and between the alpha and beta diastereomers, were achieved by high pressure liquid chromatography. The column eluant was collected and propoxyphene was extracted. The optical isomers were differentiated and characterized by melting points and by chemical microcrystalline tests. Using hot stage thermomicroscopy, the eutectic melting points of binary isomeric mixtures of propoxyphene bases and salts were found to be depressed about 10° and 15-30°C, respectively, below the individual isomer melting points. The characteristic microcrystals formed with the alpha racemic mixtures by using a glycerin-aqueous gold chloride reagent were not produced by the beta racemic mixtures.

scholarly journals 3D characterization of individual grains of coexisting high-pressure H2O ice phases by time-domain Brillouin scattering

2021 ◽  
Vol 130 (5) ◽  
pp. 053104
Author(s):  
Sathyan Sandeep ◽  
Théo Thréard ◽  
Elton De Lima Savi ◽  
Nikolay Chigarev ◽  
Alain Bulou ◽  
...  
Keyword(s):  
High Pressure ◽  
Time Domain ◽  
Brillouin Scattering ◽  
Individual Grains

scholarly journals Multianvil High-Pressure/High-Temperature Synthesis and Characterization of multiferroic HP-Co3TeO6

2021 ◽  
Author(s):  
Gunter Heymann ◽  
Elisabeth Selb ◽  
Toni Buttlar ◽  
Oliver Janka ◽  
Martina Tribus ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Type Structure ◽  
Synthesis And Characterization ◽  
Temperature Synthesis ◽  
Space Group ◽  
Crystal System ◽  
High Temperature Synthesis ◽  
High Pressure High Temperature

By high-pressure/high-temperature multianvil synthesis a new high-pressure (HP) phase of Co3TeO6 was obtained. The compound crystallizes in the acentric trigonal crystal system of the Ni3TeO6-type structure with space group R3...

Characterization of multiple sclerosis neuroinflammation and neurodegeneration with relaxation and diffusion basis spectrum imaging

2021 ◽  
pp. 135245852110233
Author(s):  
Irene M Vavasour ◽  
Peng Sun ◽  
Carina Graf ◽  
Jackie T Yik ◽  
Shannon H Kolind ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Specific Information ◽  
Axonal Loss ◽  
Normal Appearing White Matter ◽  
Relapsing Remitting ◽  
Tissue Changes ◽  
Spectrum Imaging ◽  
Magnetic Resonance Imaging Mri ◽  
And Diffusion

Background: Advanced magnetic resonance imaging (MRI) methods can provide more specific information about various microstructural tissue changes in multiple sclerosis (MS) brain. Quantitative measurement of T1 and T2 relaxation, and diffusion basis spectrum imaging (DBSI) yield metrics related to the pathology of neuroinflammation and neurodegeneration that occurs across the spectrum of MS. Objective: To use relaxation and DBSI MRI metrics to describe measures of neuroinflammation, myelin and axons in different MS subtypes. Methods: 103 participants (20 clinically isolated syndrome (CIS), 33 relapsing-remitting MS (RRMS), 30 secondary progressive MS and 20 primary progressive MS) underwent quantitative T1, T2, DBSI and conventional 3T MRI. Whole brain, normal-appearing white matter, lesion and corpus callosum MRI metrics were compared across MS subtypes. Results: A gradation of MRI metric values was seen from CIS to RRMS to progressive MS. RRMS demonstrated large oedema-related differences, while progressive MS had the most extensive abnormalities in myelin and axonal measures. Conclusion: Relaxation and DBSI-derived MRI measures show differences between MS subtypes related to the severity and composition of underlying tissue damage. RRMS showed oedema, demyelination and axonal loss compared with CIS. Progressive MS had even more evidence of increased oedema, demyelination and axonal loss compared with CIS and RRMS.

scholarly journals High-pressure synthesis and characterization of the non-centrosymmetric scandium borate ScB6O9(OH)3

2020 ◽  
Vol 75 (6-7) ◽  
pp. 597-603
Author(s):  
Birgit Fuchs ◽  
Hubert Huppertz
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Pressure High Temperature ◽  
Structure Solution ◽  
Temperature Experiment ◽  
Pressure Synthesis

AbstractThe non-centrosymmetric scandium borate ScB6O9(OH)3 was obtained through a high-pressure/high-temperature experiment at 6 GPa and 1473 K. Single-crystal X-ray diffraction revealed that the structure is isotypic to InB6O9(OH)3 containing borate triple layers separated by scandium layers. The compound crystallizes in the space group Fdd2 with the lattice parameters a = 38.935(4), b = 4.4136(4), and c = 7.6342(6) Å. Powder X-ray diffraction and vibrational spectroscopy were used to further characterize the compound and verify the proposed structure solution.

Magnetic Characterization of SUS316L Deformed by High Pressure Torsion

2011 ◽  
Vol 239-242 ◽  
pp. 1300-1303
Author(s):  
Hong Cai Wang ◽  
Minoru Umemoto ◽  
Innocent Shuro ◽  
Yoshikazu Todaka ◽  
Ho Hung Kuo
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Stainless Steel ◽  
Phase Transformation ◽  
Austenitic Stainless Steel ◽  
Volume Fraction ◽  
High Pressure Torsion ◽  
Austenitic Matrix ◽  
Magnetic Characterization

SUS316L austenitic stainless steel was subjected to severe plastic deformation (SPD) by the method of high pressure torsion (HPT). From a fully austenitic matrix (γ), HPT resulted in phase transformation from g®a¢. The largest volume fraction of 70% a¢ was obtained at 0.2 revolutions per minute (rpm) while was limited to 3% at 5rpm. Pre-straining of g by HPT at 5rpm decreases the volume fraction of a¢ obtained by HPT at 0.2rpm. By HPT at 5rpm, a¢®g reverse transformation was observed for a¢ produced by HPT at 0.2rpm.

Femtosecond pump-probe characterization of high-pressure grown Al x Ga 1-x N single crystals

2009 ◽  
Author(s):  
Jie Zhang ◽  
A. Belousov ◽  
S. Katrych ◽  
J. Jun ◽  
J. Karpinski ◽  
...  
Keyword(s):  
High Pressure ◽  
Single Crystals ◽  
Pump Probe
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