scholarly journals Identification, Optimization and Preliminary X-ray Diffraction of a New Crystal Form of the N-terminal Domain of the HIV-1 CA Protein

2007 ◽  
Vol 6 (1) ◽  
Author(s):  
Ryan Van Woerkom ◽  
Andrew Dixon ◽  
Rob Oslund ◽  
Bruce Howard
Keyword(s):  
Crystal Form ◽  
X Ray Diffraction ◽  
X Ray ◽  
Terminal Domain ◽  
Single Protein ◽  
Intersubunit Interactions ◽  
Optimized Conditions ◽  
Mature Virus ◽  
Hiv 1 ◽  
Better Than

In an effort to better understand the detailed intersubunit interactions of the N-terminal Domain of the CA (capsid) protein from HIV-1 within the conical core of the mature virus, we have identified a novel crystal form of this domain and have optimized conditions to grow single protein crystals suitable for x-ray analysis. These high quality crystals diffract to better than 1.8 Å resolution on a rotating anode generator.

Preparation, Characterization and Hemostatic Properties of Chitosan Caffeates

2019 ◽  
Vol 814 ◽  
pp. 365-371
Author(s):  
Si Tong Lu ◽  
Dong Ying Zhang ◽  
Zhang Hu ◽  
Si Dong Li ◽  
Pu Wang Li
Keyword(s):  
Caffeic Acid ◽  
Freeze Drying ◽  
Water Solubility ◽  
Crystal Form ◽  
Positive Control ◽  
Mass Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Yunnan Baiyao ◽  
Better Than

In this paper, chitosan and caffeic acid were used as starting materials to prepare chitosan caffeates by reflux-heating and freeze-drying. The structures of chitosan caffeates were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and potentiometric titration. At the same time, the physical properties of chitosan caffeates were tested and the hemostatic properties were evaluated. The results showed that four chitosan caffeates with different mass ratios of chitosan and caffeic acid (1:1, 1:2, 1:4, 1:6) had been successfully prepared, which enhanced the water solubility. FTIR analysis demonstrated that caffeic acid had been successfully grafted onto chitosan chains. XRD showed that the crystal form of chitosan changed to some extent and the chain had some regularity in some directions, but its crystallinity reduced. Chitosan caffeates, particularly mass ratio of 1:1, showed excellent hemostatic properties and even better than chitosan and the positive control (Yunnan Baiyao), which were expected to be developed as an effective biomaterial for hemostasis.

scholarly journals Squeezing out the Catalysts: The Disulphide Bond Exchange in Aryl Disulphides at High Hydrostatic Pressure

2020 ◽  
Author(s):  
Szymon Sobczak ◽  
Paulina Ratajczyk ◽  
Andrzej Katrusiak
Keyword(s):  
Diamond Anvil Cell ◽  
Crystal Form ◽  
Disulphide Bond ◽  
X Ray Diffraction ◽  
Exchange Reactions ◽  
X Ray ◽  
Equilibrium Reactions ◽  
Diamond Anvil ◽  
Optimized Conditions ◽  
Pure Single Crystal

Exchange of the disulphide bond is a prominent example of equilibrium reactions. Therefore, the wide library of disulphide exchange reactions requires the application of catalysts, such as reducing agents, strong bases, ultraviolet light, or ultrasounds to stimulate higher conversion yields. We employed the pressure between 100 and 400 MPa, for promoting the exchange reactions between various homodimeric aryl disulphides and for optimized conditions obtained 100 % yields and pure single-crystal form of the heterodimer. The reactions were performed in a diamond-anvil cell, as well as in a hydraulic piston-and-cylinder press, and the products were characterized by X-ray diffraction, mass and NMR spectroscopy. <br>

scholarly journals Squeezing out the Catalysts: The Disulphide Bond Exchange in Aryl Disulphides at High Hydrostatic Pressure

2020 ◽  
Author(s):  
Szymon Sobczak ◽  
Paulina Ratajczyk ◽  
Andrzej Katrusiak
Keyword(s):  
Diamond Anvil Cell ◽  
Crystal Form ◽  
Disulphide Bond ◽  
X Ray Diffraction ◽  
Exchange Reactions ◽  
X Ray ◽  
Equilibrium Reactions ◽  
Diamond Anvil ◽  
Optimized Conditions ◽  
Pure Single Crystal

Exchange of the disulphide bond is a prominent example of equilibrium reactions. Therefore, the wide library of disulphide exchange reactions requires the application of catalysts, such as reducing agents, strong bases, ultraviolet light, or ultrasounds to stimulate higher conversion yields. We employed the pressure between 100 and 400 MPa, for promoting the exchange reactions between various homodimeric aryl disulphides and for optimized conditions obtained 100 % yields and pure single-crystal form of the heterodimer. The reactions were performed in a diamond-anvil cell, as well as in a hydraulic piston-and-cylinder press, and the products were characterized by X-ray diffraction, mass and NMR spectroscopy. <br>

scholarly journals Squeezing out the Catalysts: The Disulphide Bond Exchange in Aryl Disulphides at High Hydrostatic Pressure

2020 ◽  
Author(s):  
Szymon Sobczak ◽  
Paulina Ratajczyk ◽  
Andrzej Katrusiak
Keyword(s):  
Diamond Anvil Cell ◽  
Crystal Form ◽  
Disulphide Bond ◽  
X Ray Diffraction ◽  
Exchange Reactions ◽  
X Ray ◽  
Equilibrium Reactions ◽  
Diamond Anvil ◽  
Optimized Conditions ◽  
Pure Single Crystal

Exchange of the disulphide bond is a prominent example of equilibrium reactions. Therefore, the wide library of disulphide exchange reactions requires the application of catalysts, such as reducing agents, strong bases, ultraviolet light, or ultrasounds to stimulate higher conversion yields. We employed the pressure between 100 and 400 MPa, for promoting the exchange reactions between various homodimeric aryl disulphides and for optimized conditions obtained 100 % yields and pure single-crystal form of the heterodimer. The reactions were performed in a diamond-anvil cell, as well as in a hydraulic piston-and-cylinder press, and the products were characterized by X-ray diffraction, mass and NMR spectroscopy. <br>

scholarly journals Born out of Fire and Ice: Polymorph Studies of the Antiviral Famciclovir

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 129
Author(s):  
Liana Vella-Zarb ◽  
Ulrich Baisch
Keyword(s):  
Variable Temperature ◽  
Chemical Properties ◽  
Crystal Form ◽  
X Ray Diffraction ◽  
Crystal Forms ◽  
X Ray ◽  
Physical Chemical ◽  
Diffraction Patterns ◽  
Crystalline Forms

There is much interest and focus on solid forms of famciclovir. However, in spite of the abundance of reported differences in oral bioavailability, compressibility, and other physical–chemical properties of the various crystal forms of this drug, very little precise structural analysis is available in the literature to date. The form used in the commercial formulation is the anhydrous form I. Patents and patent applications report three different anhydrous crystalline forms on the basis of unindexed powder diffraction patterns. Single-crystal and variable-temperature X-ray diffraction experiments using the commercially available anhydrous form of famciclovir were carried out and led not only to the crystal structure determination of the anhydrous form I, but also to discovery of a new crystal form of anhydrous famciclovir from powder data.

Influence of High Current Pulsed Electron Beam Irradiation on Ni-P Electroless Plating

2011 ◽  
Vol 299-300 ◽  
pp. 77-81
Author(s):  
Yang Xu ◽  
Sheng Zhi Hao ◽  
Xiang Dong Zhang ◽  
Min Cai Li ◽  
Chuang Dong
Keyword(s):  
Electroless Plating ◽  
Electron Beam Irradiation ◽  
Xrd Analysis ◽  
High Current ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pulsed Electron Beam ◽  
6063 Aluminum Alloy ◽  
Pre Treatment ◽  
Better Than

The surface irradiation of 6063 aluminum alloy by high current pulsed electron was conducted with the aim of replacing the complicated pre-treatment in the processes of electroless plating. To explore the microstructure changes, optical metallography, SEM (scanning electron microscope), XRD (X-ray diffraction) analyses were carried out, and the sliding tests were used for the detection of wear resistance. It was concluded that the HCPEB irradiation could replace the pre-treatment of aluminum substrate as required in conventional electroless plating with a decreased surface roughness of Ni-P alloy plating layer. The plates exhibited an amorphous microstructure as demonstrated by XRD analysis. The plates, produced with the routine of HCPEB irradiation, activation and electroless plating possess, also exhibited good quality, even better than that of conventional electroless plating technique.

Structure and properties of polypropylene/organic rectorite nanocomposites

Clay Minerals ◽  
2009 ◽  
Vol 44 (1) ◽  
pp. 35-50 ◽  
Author(s):  
Yun Huang ◽  
Xiaoyan Ma ◽  
Guozheng Liang ◽  
Hongxia Yan
Keyword(s):  
Loss Modulus ◽  
Polarized Light ◽  
Clay Content ◽  
Crystal Form ◽  
Ammonium Bromide ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Monoclinic Crystal ◽  
X Ray

AbstractMelt blending using a twin-screw extruder was used to prepare composites of polypropylene (PP)/organic rectorite (PR). The organic rectorite (OREC) was modified with dodecyl benzyl dimethyl ammonium bromide (1227). Wide-angle X-ray diffraction (WAXD) and transmission electron microscopy were used to investigate the dispersion of OREC in the composites. The d spacings of OREC in PR composites was greater than in OREC itself. The dispersion of OREC particles in the PP polymer matrix was fine and uniform when the clay content was small (2 wt.%). The rheology was characterized using a capillary rheometer. The processing behaviour of the PR system improved as the amount of OREC added increased. Non-isothermal crystallization kinetics were analysed using differential scanning calorimetry. It was shown that the addition of OREC had a heterogeneous nucleation effect on PP, and can accelerate the crystallization. However, only when fine dispersion was achieved, and at lower rates of temperature decrease, was the crystallinity greater. Wide-angle X-ray diffraction and polarized light microscopy were used to observe the crystalline form and crystallite size. The PP in the PR composites exhibited an a-monoclinic crystal form, as in pure PP, and in both cases a spherulite structure was observed. However, the smaller spherulite size in the PR systems indicated that addition of OREC can reduce the crystal size significantly, which might improve the ‘toughness’ of the PP. The mechanical properties (tensile and impact strength) improved when the amount of OREC added was appropriate. Dynamic mechanical analysis showed that the storage modulus (E′) and loss modulus (E″) of the nanocomposites were somewhat greater than those of pure PP when an appropriate amount of OREC was added. Finally, thermogravimetric analysis showed that the PR systems exhibited a greater thermal stability than was seen with pure PP.

scholarly journals Purification, crystallization and preliminary X-ray diffraction analysis of a hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyltransferase (HCT) fromCoffea canephorainvolved in chlorogenic acid biosynthesis

2012 ◽  
Vol 68 (7) ◽  
pp. 824-828 ◽  
Author(s):  
Laura A. Lallemand ◽  
James G. McCarthy ◽  
Sean McSweeney ◽  
Andrew A. McCarthy
Keyword(s):  
Structural Data ◽  
Coffea Canephora ◽  
Molecular Replacement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Key Enzyme ◽  
Substrate Specifities ◽  
Drop Technique ◽  
Better Than

Chlorogenic acids (CGAs) are a group of soluble phenolic compounds that are produced by a variety of plants, includingCoffea canephora(robusta coffee). The last step in CGA biosynthesis is generally catalysed by a specific hydroxycinnamoyl-CoA quinate hydroxycinnamoyltransferase (HQT), but it can also be catalysed by the more widely distributed hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyltransferase (HCT). Here, the cloning and overexpression of HCT fromC. canephorainEscherichia colias well as its purification and crystallization are presented. Crystals were obtained by the sitting-drop technique at 293 K and X-ray diffraction data were collected on the microfocus beamline ID23-2 at the ESRF. The HCT crystals diffracted to better than 3.0 Å resolution, belonged to space groupP42212 with unit-cell parametersa=b= 116.1,c= 158.9 Å and contained two molecules in the asymmetric unit. The structure was solved by molecular replacement and is currently under refinement. Such structural data are needed to decipher the molecular basis of the substrate specifities of this key enzyme, which belongs to the large plant acyl-CoA-dependent BAHD acyltransferase superfamily.

scholarly journals UV-Accelerated Photocatalytic Degradation of Pesticide over Magnetite and Cobalt Ferrite Decorated Graphene Oxide Composite

Plants ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 6
Author(s):  
Asma Tabasum ◽  
Mousa Alghuthaymi ◽  
Umair Yaqub Qazi ◽  
Imran Shahid ◽  
Qamar Abbas ◽  
...  
Keyword(s):  
Spectroscopic Techniques ◽  
Combined Effects ◽  
X Ray Diffraction ◽  
Contributing Factors ◽  
Reaction Conditions ◽  
X Ray ◽  
Oxidant Concentration ◽  
Optimized Conditions ◽  
High Degradation Rate ◽  
Considerable Loss

Pesticides are one of the main organic pollutants as they are highly toxic and extensively used worldwide. The reclamation of wastewater containing pesticides is of utmost importance. For this purpose, GO-doped metal ferrites (GO-Fe3O4 and GO-CoFe2O4) were prepared and characterized using scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopic techniques. Photocatalytic potentials of catalysts were investigated against acetamiprid’s degradation. A detailed review of the parametric study revealed that efficiency of overall Fenton’s process relies on the combined effects of contributing factors, i.e., pH, initial oxidant concentration, catalyst dose, contact time, and acetamiprid load. ~97 and ~90% degradation of the acetamiprid was achieved by GO-CoFe2O4 and GO-Fe3O4, respectively during the first hour under UV radiations at optimized reaction conditions. At optimized conditions (i.e., pH:3, [H2O2]: 14.5 mM (for Fe3O4, GO-Fe3O4, and GO-CoFe2O4) and 21.75 mM (for CoFe2O4), catalysts: 100 mgL−1, time: 60min) the catalysts exhibited excellent performance, with high degradation rate, magnetic power, easy recovery at the end, and efficient reusability (up to 5 cycles without any considerable loss in catalytic activity). A high magnetic character offers its easy separation from aqueous systems using an external magnet. Moreover, the combined effects of experimental variables were assessed simultaneously and justified using response surface methodology (RSM).

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