Understanding Nucleation Mechanism of Mefenamic Acid: An Examination of Relation between Pre-assembly Structure in Solution and Nucleation Kinetics

2021 ◽  
Author(s):  
Jianhua Han ◽  
Mingtao Zhang ◽  
Mingdi Liu ◽  
Yumin Liu ◽  
Jiayin Zhang ◽  
...  
Keyword(s):  
Mefenamic Acid ◽  
Nucleation Mechanism ◽  
Nucleation Kinetics ◽  
Assembly Structure ◽  
Structure In Solution

scholarly journals On the question of two-step nucleation in protein crystallization

2015 ◽  
Vol 179 ◽  
pp. 41-58 ◽  
Author(s):  
Andrea Sauter ◽  
Felix Roosen-Runge ◽  
Fajun Zhang ◽  
Gudrun Lotze ◽  
Artem Feoktystov ◽  
...  
Keyword(s):  
Real Time ◽  
Intermediate Phase ◽  
Early Stage ◽  
Protein Crystallization ◽  
Structural Evolution ◽  
Equation Model ◽  
Nucleation Mechanism ◽  
Crystal Nucleation ◽  
Time Study ◽  
Nucleation Kinetics

We report a real-time study on protein crystallization in the presence of multivalent salts using small angle X-ray scattering (SAXS) and optical microscopy, focusing particularly on the nucleation mechanism as well as on the role of the metastable intermediate phase (MIP). Using bovine beta-lactoglobulin as a model system in the presence of the divalent salt CdCl2, we have monitored the early stage of crystallization kinetics which demonstrates a two-step nucleation mechanism: protein aggregates form a MIP, which is followed by the nucleation of crystals within the MIP. Here we focus on characterizing and tuning the structure of the MIP using salt and the related effects on the two-step nucleation kinetics. The results suggest that increasing the salt concentration near the transition zonepseudo-c** enhances the energy barrier for both MIPs and crystal nucleation, leading to slow growth. The structural evolution of the MIP and its effect on subsequent nucleation is discussed based on the growth kinetics. The observed kinetics can be well described, using a rate-equation model based on a clear physical two-step picture. This real-time study not only provides evidence for a two-step nucleation process for protein crystallization, but also elucidates the role and the structural signature of the MIPs in the nonclassical process of protein crystallization.

Kinetics of Ni-Nano Cr2O3 Composite Coating during Early Electro-Crystallization Processes

2013 ◽  
Vol 785-786 ◽  
pp. 938-943 ◽  
Author(s):  
Li Bin Yu ◽  
Qi Jun Zhong ◽  
Yi Xiao ◽  
Jian Feng Gu ◽  
Qing Dong Zhong
Keyword(s):  
Composite Coating ◽  
Composite System ◽  
Nucleation Mechanism ◽  
Crystal Nucleation ◽  
Nucleation Process ◽  
Nucleation Kinetics ◽  
Instantaneous Nucleation ◽  
Nucleation Model ◽  
Progressive Nucleation ◽  
Kinetics Of

Nucleation kinetics of Ni-nanoCr2O3composite coating during early electro-crystallization was investigated. The results showed that, the early electro-crystallization processes of Ni-nanoCr2O3composite coating and pure Ni coating followed a Scharifker-Hill nucleation/growth mechanism. At the low potential, the nucleation process of pure Ni and Ni-Cr2O3composite system may approach to the progressive nucleation model; With the overpotential increasing, the nucleation model of Pure Ni and Ni-Cr2O3composite system converts into the instantaneous nucleation mechanism controlled; at the same overpotential, Cr2O3powder promotes the electro-crystallization nucleation of Ni. But at high negative potential, Cr2O3powder in composite system promotes the electro-crystal nucleation of Ni weakly; the nanoCr2O3powder added reduces the current efficiency in the nucleation process of Ni.

AEM analysis of solidification catalysts in atomized Fe-Ni

1986 ◽  
Vol 44 ◽  
pp. 584-585
Author(s):  
Matthew R. Libera
Keyword(s):  
Powder Particle ◽  
Alloy Composition ◽  
Particle Diameter ◽  
Metastable Phases ◽  
Liquid Droplets ◽  
Nucleation Kinetics ◽  
Ni Alloys ◽  
Nonequilibrium Solidification

The liquid droplets produced by atomization processes are believed to undergo substantial supercooling during solidification, because the catalytic heterogeneities, for statistical reasons, tend to be isolated in the larger droplets. This supercooling can lead to the nucleation of metastable phases. As part of a study on the effect of liquid supercooling on nonequilibrium solidification, three binary Fe-Ni alloys have been produced by conventional argon atomization (Fe-20Ni, Fe-30Ni, and Fe-40Ni). The primary variables in these experiments are: i) the alloy composition; and ii) the powder particle diameter (inversely proportional to supercooling). Of particular interest in this system is the competitive nucleation kinetics between the stable fee and metastable bec phases. Bcc is expected to nucleate preferentially with decreasing %Ni and decreasing particle diameter.

Transmission Electron Microscopy characterization of epitaxial III-V semiconductor thin films grown on Si(100) by ion-assisted deposition

1990 ◽  
Vol 48 (4) ◽  
pp. 686-687
Author(s):  
L. Hultman ◽  
C.-H. Choi ◽  
R. Kaspi ◽  
R. Ai ◽  
S.A. Barnett
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Irradiation ◽  
High Energy ◽  
Nucleation Mechanism ◽  
Layer By Layer ◽  
Extended Defect ◽  
Island Formation ◽  
Si Substrates ◽  
Transmission Electron

III-V semiconductor films nucleate by the Stranski-Krastanov (SK) mechanism on Si substrates. Many of the extended defects present in the films are believed to result from the island formation and coalescence stage of SK growth. We have recently shown that low (-30 eV) energy, high flux (4 ions per deposited atom), Ar ion irradiation during nucleation of III-V semiconductors on Si substrates prolongs the 1ayer-by-layer stage of SK nucleation, leading to a decrease in extended defect densities. Furthermore, the epitaxial temperature was reduced by >100°C due to ion irradiation. The effect of ion bombardment on the nucleation mechanism was explained as being due to ion-induced dissociation of three-dimensional islands and ion-enhanced surface diffusion.For the case of InAs grown at 380°C on Si(100) (11% lattice mismatch), where island formation is expected after ≤ 1 monolayer (ML) during molecular beam epitaxy (MBE), in-situ reflection high-energy electron diffraction (RHEED) showed that 28 eV Ar ion irradiation prolonged the layer-by-layer stage of SK nucleation up to 10 ML. Otherion energies maintained layer-by-layer growth to lesser thicknesses. The ion-induced change in nucleation mechanism resulted in smoother surfaces and improved the crystalline perfection of thicker films as shown by transmission electron microscopy and X-ray rocking curve studies.

SAC3B is a target of CML19, the centrin 2 of Arabidopsis thaliana

2020 ◽  
Vol 477 (1) ◽  
pp. 173-189 ◽  
Author(s):  
Marco Pedretti ◽  
Carolina Conter ◽  
Paola Dominici ◽  
Alessandra Astegno
Keyword(s):  
Excision Repair ◽  
Complex Structure ◽  
Binding Motif ◽  
C Terminus ◽  
Repair Protein ◽  
Nucleotide Excision ◽  
Ef Hand ◽  
Molecular Determinants ◽  
Structure In Solution

Arabidopsis centrin 2, also known as calmodulin-like protein 19 (CML19), is a member of the EF-hand superfamily of calcium (Ca2+)-binding proteins. In addition to the notion that CML19 interacts with the nucleotide excision repair protein RAD4, CML19 was suggested to be a component of the transcription export complex 2 (TREX-2) by interacting with SAC3B. However, the molecular determinants of this interaction have remained largely unknown. Herein, we identified a CML19-binding site within the C-terminus of SAC3B and characterized the binding properties of the corresponding 26-residue peptide (SAC3Bp), which exhibits the hydrophobic triad centrin-binding motif in a reversed orientation (I8W4W1). Using a combination of spectroscopic and calorimetric experiments, we shed light on the SAC3Bp–CML19 complex structure in solution. We demonstrated that the peptide interacts not only with Ca2+-saturated CML19, but also with apo-CML19 to form a protein–peptide complex with a 1 : 1 stoichiometry. Both interactions involve hydrophobic and electrostatic contributions and include the burial of Trp residues of SAC3Bp. However, the peptide likely assumes different conformations upon binding to apo-CML19 or Ca2+-CML19. Importantly, the peptide dramatically increases the affinity for Ca2+ of CML19, especially of the C-lobe, suggesting that in vivo the protein would be Ca2+-saturated and bound to SAC3B even at resting Ca2+-levels. Our results, providing direct evidence that Arabidopsis SAC3B is a CML19 target and proposing that CML19 can bind to SAC3B through its C-lobe independent of a Ca2+ stimulus, support a functional role for these proteins in TREX-2 complex and mRNA export.

HŒMOLYTIC REACTION TO MEFENAMIC ACID

The Lancet ◽  
1971 ◽  
Vol 298 (7224) ◽  
pp. 607-608 ◽  
Author(s):  
C Kennedy
Keyword(s):  
Mefenamic Acid

Vasoactive intestinal contractor (VIC) peptide structure in solution as determinated by proton NMR

1992 ◽  
Vol 89 ◽  
pp. 175-181 ◽  
Author(s):  
A Aumelas ◽  
L Chiche ◽  
E Brun ◽  
E Mahé ◽  
D Le Nguyen ◽  
...  
Keyword(s):  
Proton Nmr ◽  
Peptide Structure ◽  
Structure In Solution
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