Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 61 for “"pH dependence"”.
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Kinetic Analysis and pH Dependence of the Phosphite Dehydrogenase Reaction
The pH-rate profiles for active site mutants Lys76Ala, Glu266G1n, and Arg237Lys are also bell-shaped and the higher pKa of each is 8.4, which is also consistent with that observed for the pH dependence of sulfite inhibition for the wild type enzyme. Interestingly, the acidic limb of the Glu266Gln …
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Ph-dependence of the quaternary structure of the cyanide dihydratase from bacillus pumilus
… activation (Rhodococcus rhodocrous) and pH change as is the case for the Cyanide dihydratase from Bacilluspumilus Cl (CynDpum) which exists as a terminating spiral of -16 subunits above pH 6 but forms a long helical fibre below -pH 6. In this project the Cyanide dihydratase from strain …
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Rheological Study of Concentrated Silica Suspensions
… The viscometric data was analyzed for shear dependence, solid concentration dependence and pH dependence. The data for electrophoretic mobility was analyzed for pH dependence.</p><p>The experimental data was applied to the Bingham plastic model and the power law model and the power law model …
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A Comparison of Light-Activated Enzymes From Vertebrate and Invertebrate Photoreceptors
… search for light-activated enzymes in octopus photoreceptors analogous to those found in vertebrates' photoreceptors, (2) the question of which photointermediate(s) of photoexcited rhodopsin activate bovine photoreceptor GTPase, and (3) the calcium and pH dependence of phosphodiesterase in …
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Etching and chemomechanical polishing of compound semiconductors using halogen-based reagents
… and the production of a polished substrate. The pH dependence of sodium hypochlorite is explained in terms of its composition. At low pH (<8) the main component of the etchant solution is dichlorine. At high pH (>8) the main component of the etchant solution is hypochlorite anion. Thus …
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Quantifying passive drug transport across lipid membranes
… mediated fluoroquinolone transport. We study the pH dependence of antibiotic transport both through pure phospholipid membranes and through OmpF, and present a physical mechanism to explain the pH dependence of E. coli fluoroquinolone susceptibility. We also show the importance of lipid …
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Electro-reduction of bromate on mercury
… ca. -0.120 V, approximate first order activity dependences for both BrO⁻₃ and the accompanying cation, and no pH dependence. A reaction scheme is proposed which involves BrO⁻₃ "bridged" to the electrode by the accompanying cation. It is suggested that the "bridging" is a result of ion-pairing in …
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Characterization of CAXCK31, a Bacterial Calcium/Proton Antiporter
… The results from a variety of biochemical and biophysical experiments demonstrated that CAXCK31 exists as a dimer in the membrane and can be purified in the dimeric state. The methods used include chemical cross-linking, FRET, and SEC-MALS. In addition, various transport properties of CAXCK31, …
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Flavin Amine Oxidases from the Monoamine Oxidase Structural Family Utilize a Hydride Transfer Mechanism
… the oxidation of N1-acetylated polyamines. The pH-dependence of the kcat/Kamine indicates that the monoprotonated form of the substrate is required for catalysis, with the N4 nitrogen next to the site of CH bond cleavage being unprotonated. Stopped-flow spectroscopy shows that the pH-dependence …
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Synthesis Of N-Acetyl And C-Tert-Butyl Natural Amino Acid Substrates That Mimic Residues Of Polypeptides And Their Reactivity With [feiv(o)(n4py)]2+: Kinetic And Mechanistic Investigations
… their reaction with [FeIV(O)(N4Py)]2+. An electrophilic aromatic substitution mechanism is suggested for the mechanism of the reaction of the substrate derived from Phe with [FeIV(O)(N4Py)]2+.</p> <p>The second chapter focuses on the oxidation of glutathione by metal-based oxidants, both single …
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Investigation of the Interaction Between Cytochrome b(H) and the Q(i)-Site in Rhodobacter Sphaeroides
… Notable findings of this work are that the pH dependence of the midpoint potential of cytochrome bH differs substantially from what was published previously; a high potential component of bH remains even in the presence of Antimycin, and the thermodynamic properties of bH are substantially …
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Control of Ligand Binding to Heme Proteins: The Role of The Distal Histidine
… The recombination was measured using flash photolysis from 300 to 40 K, on a time scale of 100 ns to 300 s. Lowering the pH of the solution from 7.0 to 5.0, we find a 3 kJ/mol and 1.5 kJ/mol decrease in the final barrier for CO binding to myoglobin and the separated chains of human …
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Advanced electrochemical characterization of copper deposition
… steps have been found to be responsible for the pH-dependence of the electrodeposition reaction. It is also reported, although not well understood, that the presence of Fe2+ ions affects the reaction kinetics. In this work, the kinetics of copper electrodeposition were studied using alternating …
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Electron Transfer on the Donor and Acceptor Sides of Photosystem II Explored by Site-Directed Mutagenesis and Kinetic Spectroscopy
… N191 > A,D,L,$ had only small effects on the pH-dependence of the rate of Q$\rm\sb{A}\sp-$ and oxidized $\rm Y\sb{Z}$ recombination. On the other hand, E189D mutant showed a pH-independent in rate of $\rm Q\sb{A}\sp-$ and oxidized $\rm Y\sb{Z}$ recombination. Based on these data, a simple …
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Mechanistic Studies of Interfacial Proton-Coupled Electron Transfer to Molecularly Defined Surface Sites
… contrast to standard heterogeneous surfaces, graphite-conjugated carboxylate (GC COOH) electrodes display stable, isolated, unique, and atomically precise active sites. Investigating I-PCET at GC-COOH electrodes therefore introduces unprecedented clarity into the chemical nature of surface-H …
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The Sorption of Roxarsone, an Organoarsenical Animal Feed Additive
… Sorption to the Ap soils demonstrated stronger pH dependence than did sorption to the Bt soils. Removing organic matter (OM) from Ap soils significantly changed the sorption characteristics, suggesting that OM may be coating mineral surfaces in these soils. Results of this study have …
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Surface enhanced resonance Raman spectroscopy of dyes: semi-quantitative trace analysis
… possible, with respect to concentration and pH dependence. SERS and/or SERRS vibrational bands provided unique fingerprint spectra for each dye molecule. In an attempt to develop novel applications of SERRS the technique has been used, in a kinetic investigation, to monitor and analyse the …
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DNA-colloid systems and micro-rheology
… size. Chapter 4 looks at tuning the hydrophobicity of silica particles using poly(L)lysinepolyethylene glycol (PLL-PEG). We find an incubation pH dependence on their coverage. From analysing video microscopy trajectories, PLL-PEG coated beads sedimented onto A-DNA brushes are found to be …
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Quantification of the Binding of Insulin-like Growth Factor-I (IGF-I) and IGF Binding Protein-3 (IGFBP-3) Using Surface Plasmon Resonance
… studies from our laboratory show that there is a pH dependence in the association of IGF-I with the cell surface in the presence of IGFBP-3 which suggested increased association of IGF-I with IGFBP-3 at low pH. We studied cell free interaction of IGF-I and IGFBP-3 as a function of pH using surface …
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Kinetic and Mass Spectrometric Characterization of Anti-Greening Mechanisms of Cysteine and Glutathione in Chlorogenic Acid-Lysine Solutions
… captured the time- and thiol concentration-dependence of greening in chlorogenic acid-lysine-thiol solutions at pH 8.0 and 9.0, illustrating the pH-dependence of each thiol’s effectiveness at lowering terminal greening magnitude as well as glutathione’s prolonging of the lag time prior to …
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