scholarly journals Identification of Hydroxyl Protons, Determination of Their Exchange Dynamics, and Characterization of Hydrogen Bonding in a Microcrystallin Protein

2010 ◽  
Vol 132 (9) ◽  
pp. 3187-3195 ◽  
Author(s):  
Vipin Agarwal ◽  
Rasmus Linser ◽  
Uwe Fink ◽  
Katja Faelber ◽  
Bernd Reif
Keyword(s):  
Hydrogen Bonding ◽  
Hydroxyl Protons

scholarly journals A detailed picture of a protein–carbohydrate hydrogen-bonding network revealed by NMR and MD simulations

Glycobiology ◽  
2020 ◽  
Author(s):  
Gustav Nestor ◽  
Alessandro Ruda ◽  
Taigh Anderson ◽  
Stefan Oscarson ◽  
Göran Widmalm ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Antiviral Agents ◽  
Md Simulations ◽  
Protein Backbone ◽  
Carbohydrate Ligands ◽  
Hydrogen Bonding Network ◽  
Dynamics Simulations ◽  
Hydroxyl Protons

Abstract Cyanovirin-N (CV-N) is a cyanobacterial lectin with antiviral activity towards HIV and several other viruses. Here, we identify mannoside hydroxyl protons that are hydrogen bonded to the protein backbone of the CV-N domain B binding site, using NMR spectroscopy. For the two carbohydrate ligands Manα(1→2)ManαOMe and Manα(1→2) Manα(1→6)ManαOMe five hydroxyl protons are involved in hydrogen-bonding networks. Comparison with previous crystallographic results revealed that four of these hydroxyl protons donate hydrogen bonds to protein backbone carbonyl oxygens in solution and in the crystal. Hydrogen bonds were not detected between the side chains of Glu41 and Arg76 with sugar hydroxyls, as previously proposed for CV-N binding of mannosides. Molecular dynamics simulations of the CV-N/Manα(1→2)Manα(1→6)ManαOMe complex confirmed the NMR-determined hydrogen-bonding network. Detailed characterization of CV-N/mannoside complexes provides a better understanding of lectin-carbohydrate interactions and opens up to the use of CV-N and similar lectins as antiviral agents.

KAJIAN ADSORPSI Ag(S2O3)23- DALAM LIMBAH FOTOGRAFI PADA ADSORBEN KITIN DAN ASAM HUMAT TERIMOBILISASI PADA KITIN

2007 ◽  
Vol 9 (2) ◽  
pp. 58
Author(s):  
Fitri Khoerunnisa ◽  
Sri Juari Santosa ◽  
Eko Sri Kunarti
Keyword(s):  
Hydrogen Bonding ◽  
Humic Acid ◽  
Peat Soil ◽  
Crab Shell ◽  
Dominant Mechanism ◽  
Initial Concentration ◽  
Adsorption Condition ◽  
Synthetic Solution

This work was started with isolation of humic acid from peat soil and chitin from crab shell, immobilization of humic acid on chitin, and characterization of adsorbents of C and HAC. Optimum condition was studied by interacting the adsorbents with Ag(S2O3)23- in a synthetic solution on various  of pH from 2 to 10. Adsorption rate was studied by interacting the adsorbent with Ag(S2O3)23- in the synthetic solution on various time from 2 to 120 minutes. The determination of the energy and the capacity of adsorption were studied by interacting the adsorbent with Ag(S2O3)23- on various initial concentration from 2 to 75 ppm. Moreover, the mechanism of adsorption was studied by applying a sequential desorption using H2O, Na2EDTA 0.1 M, KSCN 0.5 M, and KOH 1 M. The adsorption of Ag(S2O3)23- in photography wastewater on C and on HAC were studied at the same condition as obtained for the synthetic solution. The result showed that pH 2 was the optimum adsorption condition for Ag(S2O3)23- in the synthetic solution on both C and HAC adsorbents. Ag(S2O3)23- in the synthetic solution was chemically adsorbed on C and on HAC, involving energy adsorption of 22.74–23.30 kJ/mole, respectively. Adsorption of Ag(S2O3)23- on C was faster than that on HAC with the rate constants for adsorbent C and HAC were 73 x 10-4 and 46 x 10-4 minute-1, respectively. Adsorption capacity of Ag(S2O3)23- on C and on HAC were 2.107 x 10-4 and 1.818 x 10-4 mole/g, respectively. The amount of Ag(S2O3)23- in photography wastewater that was adsorbed on C and on HAC were 13.52 and 12.47 mg/L, respectively. The hydrogen bonding and ion exchange were the dominant mechanism of adsorption.Key words: Ag(S2O3)23-, adsorption, chitin, immobilization, humic acid.

Characterization of Impressed Current Technique to Model Corrosion of Reinforcement in Concrete

2020 ◽  
Vol 11 (1) ◽  
pp. 93-99
Author(s):  
Abu Zakir Morshed ◽  
Sheikh Shakib ◽  
Tanzim Jahin
Keyword(s):  
Immersion Time ◽  
Chloride Content ◽  
Engineering Science ◽  
Coastal Regions ◽  
Faraday’S Law ◽  
Current Technique ◽  
Corrosion Cell ◽  
Impressed Current

Corrosion of reinforcement is an important durability concern for the structures exposed to coastal regions. Since corrosion of reinforcement involves long periods of time, impressed current technique is usually used to accelerate the corrosion of reinforcement in laboratories. Characterization of impressed current technique was the main focus of this research,which involved determination of optimum chloride content and minimum immersion time of specimens for which the application of Faraday’s law could be efficient. To obtain optimum chloride content, the electrolytes in the corrosion cell were prepared similar to that of concrete pore solutions. Concrete prisms of 200 mm by 200 mm by 300 mm were used to determine the minimum immersion time for saturation. It was found that the optimum chloride content was 35 gm/L and the minimum immersion time for saturation was 140 hours. Accounting the results, a modified expression based on Faraday’s law was proposed to calculate weight loss due to corrosion. Journal of Engineering Science 11(1), 2020, 93-99

The Determination of Sense via Deleuze and Blanchot: Paradoxes of the Habitual, the Immemorial, and the Eternal Return

2008 ◽  
Vol 2 (2) ◽  
pp. 155-177 ◽  
Author(s):  
Eugene Brently Young
Keyword(s):  
Eternal Return

Eternal return is the paradox that accounts for the interplay between difference and repetition, a dynamic at the heart of Deleuze's philosophy, and Blanchot's approach to this paradox, even and especially through what it elides, further illuminates it. Deleuze draws on Blanchot's characterisations of difference, forgetting, and the unlivable to depict the ‘sense’ produced via eternal return, which, for Blanchot, is where repetition implicates or ‘carries’ pure difference. However, for Deleuze, difference and the unlivable are also developed by the living repetition or ‘contraction’ of habit, which results in his distinctive characterization of ‘force’, ‘levity’, and sense in eternal return.

SEM/EDS Characterization of Uncommon Metal Whiskers and Determination of Underlying Growth Mechanisms

2018 ◽  
Author(s):  
D. Basak ◽  
L. H. Ponce
Keyword(s):  
Reliability Analysis ◽  
Case Studies ◽  
Whisker Growth ◽  
Innovation Systems ◽  
Growth Mechanisms ◽  
Crystal Oscillator ◽  
Analysis Laboratory ◽  
Investigative Techniques

Abstract Two case-studies on uncommon metals whiskers, performed at the Reliability Analysis Laboratory (RAL) of Northrop Grumman Innovation Systems, are presented. The components analyzed are an Oven Controlled Crystal Oscillator (OCXO) and an Electromechanical Relay. Investigative techniques were used to determine the chemical and physical makeup of the metal whiskers and develop an understanding of the underlying effects and mechanisms that caused the conditions conducive to whisker growth.

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