Search results for "Titration"

showing 10 items of 312 documents

Structural Basis of the High Affinity Interaction between the Alphavirus Nonstructural Protein-3 (nsP3) and the SH3 Domain of Amphiphysin-2

2016

We show that a peptide from Chikungunya virus nsP3 protein spanning residues 1728–1744 binds the amphiphysin-2 (BIN1) Src homology-3 (SH3) domain with an unusually high affinity (Kd 24 nM). Our NMR solution complex structure together with isothermal titration calorimetry data on several related viral and cellular peptide ligands reveal that this exceptional affinity originates from interactions between multiple basic residues in the target peptide and the extensive negatively charged binding surface of amphiphysin-2 SH3. Remarkably, these arginines show no fixed conformation in the complex structure, indicating that a transient or fluctuating polyelectrostatic interaction accounts for this …

0301 basic medicinenuclear magnetic resonance (NMR)Amino Acid MotifsStatic ElectricityPeptideTarget peptidePlasma protein bindingViral Nonstructural ProteinsBiologyhost-pathogen interactionBiochemistrySH3 domainsrc Homology Domainsamphiphysin SH3Structure-Activity Relationship03 medical and health sciencesProtein structuredynaminHumansShort linear motifprotein structureNuclear Magnetic Resonance BiomolecularMolecular BiologySrc homology 3 domain (SH3 domain)Adaptor Proteins Signal Transducingchemistry.chemical_classificationTumor Suppressor Proteinsta1182Nuclear ProteinsIsothermal titration calorimetryCell Biologyintrinsically disordered protein030104 developmental biologychemistryBiochemistrynsP3Protein Structure and FoldingAmphiphysinBiophysicsPeptidesChikungunya virusProtein BindingJournal of Biological Chemistry
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Thermomineral waters of Greece: geochemical characterization

2020

75 °C). In terms of pH most results vary from 5.5 to 823 °C) ii) warm (23 40 °C) iii) thermal (40 75 °C) and iv) hyperthermal (&gtfew springs show either very low pH (&lt10) proposing serpentinization processes. Regarding TDS concentrations collected waters can be subdivided into low salinity (up to 1.5 g/L) brackish (up to 20 g/L) and saline (up to 43 g/L). The medium high salinities can be justified by mixing with sea water and/or strong waterrock interaction processes. Isotope composition of O and H ranges from 12.7 to +2.7 ‰ SMOW and from 91 to +12 ‰ SMOW respectively and is generally comprised between the Global Meteoric Water Line and the East Mediterranean Meteoric Water Line. Only few water samples show a positive shift for δ18O possibly related to high temperature waterrock interaction processes. Carbon dioxide (18 997000 μmol/mol) or N2 (1100 989000 μmol/mol) or CH4 (&ltMany geothermal areas of Greece are located in regions affected by Miocene or Quaternary volcanism and in continental basins characterised by elevated heat flow. Moreover the majority of them is found along the coast as well as in islands of the Aegean Sea and thus thermal water is often brackish to saline due to marine intrusion into costal aquifer. In the present study almost 300 thermal and cold mineral water samples were collected along the Hellenic territory with their physicochemical parameters (temperature pH electrical conductivity and Eh) and the amount of bicarbonates (titration with 0.1N HCl) being determined in situ. Additionally gases found either in free or dissolved phase were sampled. Both water and gas samples were analysed at the INGVPa laboratories for major ions (Ion Chromatography) silica (Inductively Coupled Plasma Optical Emission Spectrometry) chemical composition of free and dissolved gases (Gas Chromatography) water isotopes (O and H) and carbon and helium isotopes of free and dissolved gases (Mass Spectrometry). The temperature of the investigated waters ranges from 6.5 to 98°C pH from 1.96 to 11.98 whilst Total Dissolved Solids (TDS) from 0.06 to 43 g/L. Based on the temperature parameter waters can be divided into four groups: i) cold (&lt0.5 913000 μmol/mol) are the prevailing gas species found in the studied sites. The δ13CCO2 values ranged from 20.1 to +8.5 ‰ whilst the isotope ratio of He from 0.21 to 6.71 R/RA.4) suggesting interaction with H2Srich gases or very high pH values (&gtSettore GEO/08 - Geochimica E Vulcanologia
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Dioxouranium(VI) hydrolysis at 75 and 100°C in 3.6 molkg-1 LiClO4

2008

This work concerns the acidic properties of uranyl ion UO22+ at 75 and 100 °C in 3.6 molal (molkg-1 solvent) LiClO4 aqueous medium. The investigation was carried out by a coulometric-potentiometric technique. Direct and reverse acid base titrations were carried out in order to check the achievement of actual equilibrium conditions. Moreover, in order to reveal oversaturation conditions, a further check was carried out on clean saturated hydrolyzed solutions.

Acid-base titrations check of equilibrium conditions hydrolysis in hot LiClO4 aqueous medium.Settore CHIM/01 - Chimica Analitica
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Modeling S-carboxymethyl-L-cysteine protonation and activity coefficients in sodium and tetramethylammonium chloride aqueous solutions by SIT and Pit…

2007

Solubility and acid–base properties of S-carboxymethyl-l-cysteine (carbocysteine, ccys) in NaClaq and tetramethylammonium chloride, (CH3)4NClaq ,a tt =2 5 ◦ C and at different ionic strengths were investigated. Solubility was studied at 1.0 ≤ I (mol L −1 ) ≤ 5.0 for NaClaq and 1.0 ≤ I (mol L −1 ) ≤ 3.0 for (CH3)4NClaq, while potentiometric measurements (by ISE-H + , glass electrode) were performed at 0.1 ≤ I (mol L −1 ) ≤ 5.0 for NaClaq and 0.5 ≤ I (mol L −1 ) ≤ 3.0 for (CH3)4NClaq. Solubility data allowed us to determine Setschenow constants and activity coefficients of neutral carbocysteine (H2ccys). Dependence on ionic strength and ionic medium of protonation constants and activity coeff…

Activity coefficientChemistryGeneral Chemical EngineeringPotentiometric titrationInorganic chemistryAnalytical chemistryGeneral Physics and AstronomyProtonationchemistry.chemical_compoundSpecific ion interaction theoryIonic strengthTetramethylammonium chloridePitzer equationsPhysical and Theoretical ChemistrySolubilityCarbocysteine; Solubility; Protonation; Activity coefficients; Dependence on medium and ionic strength
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Modeling ATP protonation and activity coefficients in NaClaq and KClaq by SIT and Pitzer equations.

2006

Abstract The acid–base properties of Adenosine 5′-triphosphate (ATP) in NaCl and KCl aqueous solutions at different ionic strengths (0  I  / mol L − 1  ≤ 5 for NaCl aq , 0  I  / mol L − 1  ≤ 3 for KCl aq ) and at t  = 25 °C were investigated. A selection of literature data on ATP protonation constants and on activity isopiestic coefficients was performed, together with new potentiometric measurements (by ISE-H + , glass electrode). Both literature and new experimental data were used to model the dependence on ionic strength and ionic medium of ATP protonation by SIT (Specific ion Interaction Theory) and Pitzer equations. In addition to values of first and second ATP protonation constants in…

Activity coefficientMolar concentrationactivity coefficientsActivity coefficientPotentiometric titrationInorganic chemistryBiophysicsIonic bondingProtonationProtonationATP; protonation; activity coefficients; Dependence on medium and ionic strength; SIT model; Pitzer modelSodium ChlorideBiochemistryPotassium ChlorideAdenosine TriphosphateElectrochemistrySettore CHIM/01 - Chimica AnaliticaChemistryOrganic ChemistryOsmolar ConcentrationPitzer modelSIT modelATPSpecific ion interaction theoryIonic strengthDependence on medium and ionic strengthPhysical chemistryPitzer equationsBiophysical chemistry
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Coordination properties of adenosine-5'-monophosphate and related ligands towards Me2Sn(IV)2+ in aqueous solution.

2002

Abstract The coordination of Me 2 Sn(IV) 2+ to adenosine-5′-monophosphate (AMP) and the related compounds d -ribose-5-phosphate (R5P), d -glucose-1-phosphate (G1P) and d -glucose-6-phosphate (G6P) in aqueous solution was investigated by means of potentiometric titration, and 1 H-, 31 P-NMR and Mossbauer spectroscopic methods in the pH range 2–11 ( I =0.1 M NaClO 4 , 298 K). The complex of AMP and Me 2 Sn(IV) 2+ precipitated at low pH was characterised by elemental analysis, FT-IR and Mossbauer spectroscopic methods. From a comparison of the p K values obtained in the presence and absence of metal ion and the stability constants for the different systems, the coordination of {N} is excluded,…

Adenosine monophosphateDenticityMagnetic Resonance SpectroscopyPotentiometric titrationInorganic chemistryMolecular Sequence DataLigandsBiochemistryInorganic ChemistryMetalchemistry.chemical_compoundSpectroscopy MossbauerDeprotonationMössbauer spectroscopySpectroscopy Fourier Transform InfraredOrganotin CompoundsAqueous solutionMolecular StructureHydrolysisGlucosephosphatesDNAHydrogen-Ion ConcentrationPhosphateAdenosine MonophosphateSolutionsCrystallographychemistryvisual_artvisual_art.visual_art_mediumPotentiometryThermodynamicsJournal of inorganic biochemistry
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Marine sponge collagen: isolation, characterization and effects on the skin parameters surface-pH, moisture and sebum

2002

A previously described isolation procedure for collagen of the marine sponge Chondrosia reniformis Nardo was modified for scaling-up reasons yielding 30% of collagen (freeze-dried collagen in relation to freeze-dried sponge). Light microscope observations showed fibrous structures. Transmission electron microscopy studies proved the collagenous nature of this material: high magnifications showed the typical periodic banding-pattern of collagen fibres. However, the results of the amino acid analysis differed from most publications, presumably due to impurities that still were present. In agreement with earlier studies, sponge collagen was insoluble in dilute acid mediums and all solvents inv…

AdultMaleChemistry PharmaceuticalPharmaceutical ScienceDosage formlaw.inventionOptical microscopelawAnimalsHumansSolubilitySkinChromatographybiologyChemistryExtraction (chemistry)HumidityGeneral MedicineHydrogen-Ion ConcentrationMiddle Agedbiology.organism_classificationPoriferaSebumSpongeBiochemistryTransmission electron microscopyFemaleTitrationCollagenDispersion (chemistry)BiotechnologyEuropean Journal of Pharmaceutics and Biopharmaceutics
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Modelling of proton and metal exchange in the alginate biopolymer.

2005

Acid-base behaviour of a commercial sodium alginate extracted from brown seaweed (Macrocystis pyrifera) has been investigated at different ionic strengths (0.1or=I/mol l(-1)or=1.0) and in different supporting electrolytes (Et4NI, NaCl, KCl, LiCl, NaCl+MgCl2), with the aim of examining the influence of ionic medium on the proton-binding capacity and of quantifying the strength of interaction with light metal ions in the perspective of speciation studies in natural aqueous systems. Potentiometric ([H+]-glass electrode) and titration calorimetric data were expressed as a function of the dissociation degree (alpha) using different models (Henderson-Hasselbalch modified, Högfeldt three parameter…

Alginic acid; Proton- and metal-binding capacity; Thermodynamic parameters; Ionic strength dependence; Models for medium dependence and ion associationProton bindingAlginatesIonic strength dependenceInorganic chemistryPotentiometric titrationIonic bondingProtonationElectrolytePhaeophytaBiochemistryAnalytical ChemistryBiopolymersGlucuronic Acidalginic acid proton and metal-binding capacity Thermodynamics parameters Ionic strength dependence models for medium dependence and ion associationAlginic acidMagnesium ionAqueous solutionMolecular StructureChemistryHexuronic AcidsProton- and metal-binding capacityThermodynamic parametersIonic strengthMetalsProtonsModels for medium dependence and ion associationAnalytical and bioanalytical chemistry
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Clinical Problems with Transdermal Fentanyl Titration from 25 to 50 μg/hr

2001

Anesthesiology and Pain Medicinebusiness.industryAnesthesiamedicineTitrationNeurology (clinical)businessOpioid analgesicsGeneral NursingFentanylmedicine.drugTransdermalJournal of Pain and Symptom Management
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Thermodynamic parameters of the interaction between Co(II) bovine carbonic anhydrase and anionic inhibitors

1992

The pH dependence of the apparent affinity constants of perchlorate for cobalt(II)bovine carbonic anhydrase II has been measured by electronic absorption spectroscopy. The obtained data have been analyzed in terms of the ionization of two acidic groups of CoBCAII, and the affinity of perchlorate for the two water-containing species of the enzyme have been estimated. Furthermore, the affinity constants of nitrate, perchlorate, and azide for CoBCAII in the temperature range 5 degrees C-30 degrees C have been determined by spectrophotometric titrations at pH 7. The affinity constants for these ligands decrease with increasing temperatures. The temperature dependence of binding was used to esti…

AnionsAzidesCarbonic anhydrase IIEnthalpyInorganic chemistrychemistry.chemical_elementBiochemistryInorganic Chemistrychemistry.chemical_compoundPerchlorateCarbonic anhydraseAnimalsPerchloric acidCarbonic Anhydrase InhibitorsCarbonic AnhydrasesNitratesPerchloratesbiologyCobaltKineticschemistrySpectrophotometrybiology.proteinThermodynamicsCattleTitrationAzideCobaltMathematicsJournal of Inorganic Biochemistry
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