Adsorption, desorption, and activity of glucose oxidase on selected clay species

1976 ◽  
Vol 22 (5) ◽  
pp. 684-693 ◽  
Author(s):  
H. W. Morgan ◽  
C. T. Corke
Keyword(s):  
Hydrogen Bonding ◽  
Protein Structure ◽  
Cation Exchange ◽  
Glucose Oxidase ◽  
Isoelectric Point ◽  
Active Form ◽  
Temperature Dependent ◽  
Specific Activities ◽  
Ph Dependent ◽  
Adsorption Desorption

The adsorption of the enzyme glucose oxidase (EC 1.1.3.4) to clays followed the pattern described for other proteins as being pH dependent. Maximum adsorption occurred at or below the isoelectric point of the enzyme. The amount of enzyme adsorbed to clay was influenced by the type of clay used, and also the saturating cations. Initially adsorbed enzyme showed low specific activities, and as amounts of enzyme adsorbed approached maximum saturation of clay, specific activities increased approaching that determined for free enzyme.The adsorption of glucose oxidase involved a temperature-independent cation-exchange mechanism, and enzyme adsorbed to surfaces of clay could be desorbed in active form by elevation of pH of suspending solution. This was followed by a slower temperature-dependent fixation, probably by hydrogen bonding, which resulted in protein being irreversibly adsorbed to clay surfaces.It is proposed that on adsorption of glucose oxidase to clay surfaces unravelling of the protein structure occurred, which allowed penetration of protein into the interlamellar spaces of montmorillonite. This proposal was based on the observed expansion of montmorillonite to 23 Å, and the decreases in amount of a second-protein lysozyme adsorbed with extended incubation times of glucose oxidase – clay complexes at pH 4.5.

Topological analysis of hydrogen bonding in protein structure

1990 ◽  
Vol 188 (2) ◽  
pp. 361-365 ◽  
Author(s):  
Boryeu MAO ◽  
Kuo-Chen CHOU ◽  
Gerald M. MAGGIORA
Keyword(s):  
Hydrogen Bonding ◽  
Protein Structure ◽  
Topological Analysis

Evaluation of bacteriophages during the treatment of sludge

2002 ◽  
Vol 46 (10) ◽  
pp. 189-194 ◽  
Author(s):  
B. Mignotte-Cadiergues ◽  
C. Gantzer ◽  
L. Schwartzbrod
Keyword(s):  
Bacteroides Fragilis ◽  
Temperature Dependent ◽  
Treatment Methods ◽  
Somatic Coliphages ◽  
Viral Contamination ◽  
Log Reduction ◽  
Ph Dependent ◽  
Somatic Coliphage ◽  
Phage Inactivation

The aim of this work was to determine the effect of liming and composting on the fate of three bacteriophages (somatic coliphages, F-RNA phages, Bacteroides fragilis phages) considered as potential indicators of viral contamination. It was shown that the three bacteriophages studied exhibited variable densities in sludge. Somatic coliphages were most abundant (104 to 105 .10 g−1 DM) then F-RNA bacteriophages (102 to 104.10 g−1 DM) and Bacteroides fragilis phages (101 to 102.10 g−1 DM). The efficacy of liming was found to be pH dependent but also sludge dependent. The pH allowing 99% elimination of somatic coliphage is close to 9 for solid sludges and close to 13.5 for liquid sludges. For composting, our findings clearly demonstrated that phage inactivation is very clearly temperature-dependent. For temperatures reaching 70°, there is a 5 log reduction in somatic coliphages while for temperature in the 50-55°C range, the drop off is only 2 log. Considering the efficacy of the treatment methods, it is clear that the well-established industrial procedures that reach temperatures in the 60-70°C range totally inactivate all 3 phages tested and present in sludge before composting.

scholarly journals Temperature-Dependent Solid-State NMR Proton Chemical-Shift Values and Hydrogen Bonding

2021 ◽  
Author(s):  
Alexander A. Malär ◽  
Laura A. Völker ◽  
Riccardo Cadalbert ◽  
Lauriane Lecoq ◽  
Matthias Ernst ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Hydrogen Bonding ◽  
Solid State ◽  
Chemical Shift ◽  
Hydrogen Bonds ◽  
Solid State Nmr ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Proton Chemical Shift ◽  
Temperature Dependent

Temperature-dependent NMR experiments are often complicated by rather long magnetic-field equilibration times, for example occurring upon a change of sample temperature. We demonstrate that the fast temporal stabilization of the magnetic field can be achieved by actively stabilizing the temperature which allows to quantify the weak temperature dependence of the proton chemical shift which can be diagnostic for the presence of hydrogen bonds. Hydrogen bonding plays a central role in molecular recognition events from both fields, chemistry and biology. Their direct detection by standard structure determination techniques, such as X-ray crystallography or cryo-electron microscopy, remains challenging due to the difficulties of approaching the required resolution, on the order of 1 Å. We herein explore a spectroscopic approach using solid-state NMR to identify protons engaged in hydrogen bonds and explore the measurement of proton chemical-shift temperature coefficients. Using the examples of a phosphorylated amino acid and the protein ubiquitin, we show that fast Magic-Angle Spinning (MAS) experiments at 100 kHz yield sufficient resolution in proton-detected spectra to quantify the rather small chemical-shift changes upon temperature variations.<br>

Structural and Dynamic Evidence for C−H···O Hydrogen Bonding in Lariat Ethers:  Implications for Protein Structure

2000 ◽  
Vol 122 (14) ◽  
pp. 3325-3335 ◽  
Author(s):  
Eric S. Meadows ◽  
Stephen L. De Wall ◽  
Leonard J. Barbour ◽  
Frank R. Fronczek ◽  
Min-Sook Kim ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Protein Structure ◽  
Lariat Ethers

scholarly journals Multicolor Emission and Photophysical Properties of Proton-Responsive Cyclometallated Iridium(III) Complex in Transparent Cation-Exchange Membrane

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 653
Author(s):  
Hajime Kamebuchi ◽  
Yu Fujimura ◽  
Taiho Yoshioka ◽  
Atsushi Okazawa ◽  
Makoto Tadokoro ◽  
...  
Keyword(s):  
Cation Exchange ◽  
Photophysical Properties ◽  
Thermal Relaxation ◽  
Polymer Chains ◽  
Cation Exchange Membrane ◽  
Quantum Yields ◽  
Transparent Film ◽  
Maximum Emission ◽  
Ph Dependent ◽  
Exchange Membrane

A transparent film allowing tunable multicolor emission based on a composite of an organometallic compound and a cation-exchange membrane has been developed, in which the cyclometallated iridium(III) complex [IrIII(4Py-ppy)3] (=tris[2-(2-pyridinyl-κN)-4-(4-pyridinyl)phenyl-κC]iridium) (1) with pH-dependent emission wavelengths has been incorporated into Nafion by cation exchange. Soaking Nafion in the solution of 1 for 24 h and exposed to buffers at pH 2, 4, and 10 resulted in maximum emission wavelengths of 587, 560, and 503 nm, respectively. The photophysical properties of 1@Nafion were also enhanced, as its maximum emission wavelength was more blue-shifted than those of 602, 564, and 503 nm in the solutions. The emission quantum yields (Φ) and lifetimes (τ) of 1@Nafion prepared under an acidic condition were up to Φ = 1.8% and τ = 0.11, 0.92 μs, which are considerably higher than the corresponding solutions of Φ = 0.5% and τ = 0.02, 0.18 μs. This is attributed to the fact that 1 is surrounded by the polymer chains of Nafion and immobilized in a relatively rigid medium, which hinders non-radiative deactivation such as thermal relaxation.

scholarly journals Twist-Bend Nematogenic Supramolecular Dimers and Trimers Formed by Hydrogen Bonding

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 175 ◽  
Author(s):  
Rebecca Walker ◽  
Damian Pociecha ◽  
Alfonso Martinez-Felipe ◽  
John MD Storey ◽  
Ewa Gorecka ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Phase Behaviour ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Smectic C ◽  
Donor And Acceptor ◽  
Nematic Phases ◽  
Selection Of ◽  
Do So ◽  
Terminal Chain

A selection of novel non-symmetric supramolecular liquid crystal dimers and trimers formed by hydrogen-bonding have been prepared and their phase behaviour characterised by polarised optical microscopy, X-ray diffraction and temperature-dependent Fourier-transform infrared spectroscopy. We mix the bent twist-bend nematogen 4-[6-(4’-cyanobiphenyl-4-yl) hexyloxy]-benzoic acid (CB6OBA) with a series of small stilbazole-based compounds 4-[(E)-2-(n-alkoxyphenyl)ethenyl]pyridines (nOS) of varying terminal chain length (n) to obtain the CB6OBA:nOS complexes. Complexes with n ≤ 7 exhibit nematic and twist-bend nematic behaviour, followed on cooling by a smectic C phase for n = 4–7, and finally, a hexatic-type smectic X phase for n = 3–7. Mixtures with n = 8–10 exhibit a smectic A phase below the conventional nematic phase, and on further cooling, a biaxial smectic Ab phase and the same hexatic-type SmX phase. Supramolecular trimers, CB6OBA:CB6OS and CB6OBA:1OB6OS, formed between CB6OBA and dimeric stilbazoles [(E)-2-(4-{[6-(4’-methoxy[1,1’-biphenyl]-4-yl)hexyl]oxy}phenyl)ethenyl]pyridine (1OB6OS) or 4-[(E)-4’-(6-{4-[(E)-2-(pyridin-4-yl)ethenyl]phenoxy}hexyl)[1,1’-biphenyl]-4- carbonitrile (CB6OS), exhibit nematic and twist-bend nematic phases, and are the first hydrogen-bonded trimers consisting of unlike donor and acceptor fragments to do so.

ETUDE SUR LA VALEUR DES CRITERES CHIMIQUES PROPOSES PAR LA COMMISSION PEDOLOGIQUE DU CANADA POUR LA CLASSIFICATION TAXONOMIQUE DES SOLS DU QUEBEC

1977 ◽  
Vol 57 (3) ◽  
pp. 233-247 ◽  
Author(s):  
ROGER W. BARIL ◽  
THI SEN TRAN
Keyword(s):  
Cation Exchange ◽  
Soil Ph ◽  
Classification System ◽  
Cation Exchange Capacity ◽  
Exchange Capacity ◽  
Taxonomic Classification ◽  
Single Test ◽  
Ph Dependent ◽  
Extractable Al

Correlations were made among chemical criteria used for taxonomic soil classificaton. The compared tests were: oxalate Δ (Fe + Al), pyrophosphate-extractable (Fe + Al), oxalate-extractable Al, pH-dependent cation exchange capacity (ΔCEC), ratios of pyrophosphate-extractable (Fe + Al) over clay or over dithionite-extractable (Fe + Al), and finally soil pH measured in 1 M NaF. Significant correlations were found among various measured parameters. However, no single test was found to be reliable as a single criterion when applied to the taxonomic classification of Quebec soils. The two chemical tests, pyrophosphate-extractable (Fe + Al) and its ratio over clay, combined with morphologic criteria appeared useful for classifying Quebec Podzols. A few soils, which presented discrepancies from chemical criteria were found difficult to classify, thus suggesting the possibility of establishing new sub-groups in the Canadain soil taxonomic classification system.

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