Showing papers on "Titration published in 1969"
TL;DR: A major hysteresis effect occurs in the pH dependence of Mw and s20,w corresponding to the hysteResis previously observed for the hydrogen ion titration of the protein.
137 citations
TL;DR: An anaerobic titration apparatus capable of titrations of 2.5 ml of solution with microliter quantities of titrant is described and no detectable O 2 leaks were observed over a 6 day period.
85 citations
TL;DR: In this article, the EDTA titration was used for the determination of the metal in organic compounds containing calcium, magnesium, zinc, barium, manganese, or cobalt.
82 citations
TL;DR: It is suggested on the basis of these results that the most likely candidates for the two additional high potential electron-accepting sites in laccase are the two diamagnetic copper atoms in the molecule and that these copper atoms would have to be present as a Cu2+-Cu2+ pair in the native molecule.
66 citations
54 citations
TL;DR: The high values of the binding constants, and the fact that denaturation destroys the specific binding of zinc to alkaline phosphatase indicates chelate formation with the protein, unless some unknown prosthetic groups are involved.
Abstract: The binding of Zn2+ to Escherichia coli alkaline phosphatase has been studied by pH titrations and equilibrium dialysis using 1,10-phenanthroline as competing chelating agent.
Measurements of the strength of binding under different experimental conditions have been performed:
1
At constant pH with different concentrations of chelating agent.
2
At different pH with constant concentration of chelating agent.
3
In the presence of denaturing agent at pH 8.0.
It was found on the basis of equilibrium dialysis experiments that the binding of the two zinc atoms to alkaline phosphatase may be described as coordination to the two equivalent and independent sites.
The high values of the binding constants, and the fact that denaturation destroys the specific binding of zinc to alkaline phosphatase indicates chelate formation with the protein, unless some unknown prosthetic groups are involved.
51 citations
TL;DR: The molecular weight of pig liver carboxylesterase has been determined as 163,000 (±15,000) and no evidence has been obtained for the dissociation of the enzyme into species of mol wt ~40,000, either at pH 8 or in 8 M urea.
Abstract: The molecular weight of pig liver carboxylesterase (~88% pure) has been determined as 163,000 (±15,000). The enzyme has two active sites per molecular weight of 163,000 as shown by titration with pnitrophenyl dimethylcarbamate and p-nitrophenyl diethyl phosphate. The enzyme undergoes slow irreversible inactivation at pH 5, but on dilution at pH 7.5, the enzyme dissociates apparently into half-molecules which are active. No evidence has been obtained for the dissociation of the enzyme into species of mol wt ~40,000, either at pH 8 or in 8 M urea.
48 citations
TL;DR: A procedure using sodium dithionite diluted with KCl and small amounts of base has been developed for anaerobic reductive titrations of proteins in conjunction with EPR and light spectroscopy, and random errors associated with such titrations appear to be commensurate with those encountered with quantitative EPR spectroscopic.
39 citations
37 citations
TL;DR: In this article, the titration curves have been analysed by rigorous equilibrium calculations with the computer program HALTAFALL, and they have been shown to enter the solid phase, forming precipitates with the formula LaF3-xAcx (0
TL;DR: In this paper, values for equilibrium, constants of metal ion-amino acid complexes have been obtained from pH titration data without imposing the arbitary restriction that only MLn species were present.
Abstract: Values for equilibrium, constants of metal ion–amino-acid complexes have been obtained from pH titration data without imposing the arbitary restriction that only MLn species were present. For several of the systems, the data were consistent with the presence of additional protonated and hydrolysed species. The solutions studied were one-metal–one-ligand aqueous systems, of copper(II), zinc(II), and manganese(II) ions, with glycine, L-alanine, L-valine, and L-proline, at 37° and 0·15M in potassium nitrate.
TL;DR: In this article, the hydrogen ion concentration of aerosol samples dissolved in neutral water was determined by titration and also by measuring the pH-value, and the results showed that most of the water soluble compounds of the aerosols were associated with particles smaller than 0.1 μ radius.
TL;DR: In this paper, a calcium-selective electrode was used to monitor EGTA and DCTA titrations of aqueous mixtures of calcium, magnesium and sodium salts.
TL;DR: In this paper, the results indicate that the tetra-n-alkylammonium ions do not associate appreciably with SO42− with H+, Na+, and K+, and of ClO4− with R4N+(R = Me, Et, and Prn), using a calorimetric titration procedure.
Abstract: Log K, ΔH°, and ΔS° values for the interaction in aqueous solution at 25° of SO42– with H+, Na+, and K+, and of ClO4– with R4N+(R = Me, Et, and Prn), have been determined using a calorimetric titration procedure. The results indicate that the tetra-n-alkylammonium ions do not associate appreciably with SO42–.
TL;DR: In this article, a solid-membrane cupric electrode was used for the complexometric titration of cupric ion with several ligands in methanol, acetone and acetonitrile.
Abstract: Use of the new, solid-membrane cupric electrode for non-aqueous titrations, a significant advancement over the earlier liquid-membrane electrode, is illustrated. The solid-membrane cupric electrode was used for the complexometric titration of cupric ion with several ligands in methanol, acetone and acetonitrile.
TL;DR: In this article, the binding of imidazole to ferriprotoporphyrin IX (hemin) in aqueous ethanol has been studied at 25° using the temperature jump technique.
Abstract: The kinetics of binding of imidazole to ferriprotoporphyrin IX (hemin) in aqueous ethanol has been studied at 25° using the temperature jump technique. The reaction was studied quantitatively as a function of acid concentration using the pH scale developed by Bates et al. for mixed solvent systems. The results can be explained by a mechanism in which the imidazolium ion binds to hemin with a specific rate constant of (4 ± 2) × 106 M−1 s−1 and imidazole binds with a rate constant of (3 ± 0.3) × 104 M−1 s−1. The dissociation constant for the imidazolium ion was determined by acid–base titration to be 1.8 × 10−7 M, and a dissociation constant for the hemin of 2.3 × 10−7 M was determined by spectrophotometric titration in a solvent containing 44.5 weight % of ethanol. The latter dissociation involves the proton on a solvent ligand.
TL;DR: Reversible and irreversible conformational changes in the acid‐induced denaturation of DNA were studied by spectrophotometric titration, sedimentation, and melting measurements and an acid denaturation scheme for a GC‐rich DNA segment is suggested.
Abstract: Reversible and irreversible conformational changes in the acid-induced denaturation of DNA were studied by spectrophotometric titration, sedimentation, and melting measurements. A GC-rich DNA (72 mole-%) shows complete or partial reversibility of the titration profiles within the pH region of transition from helix to coil, while AT-rich DNA (29 mole-%) is irreversible in its titration behavior at each acid pH below the onset of the transition. The results for GC-rich DNA further indicate distinct differences in the titration behavior, which can be attributed to differences in the frequency of GC clusters along the DNA molecule. Plots of the sedimentation coefficient and the parameter asapp against pH lead to the conclusion that conformational changes occur before the onset of the acid-induced helix–coil transition. These alterations are more pronounced upon protonation of larger GC-rich domains than of smaller ones, as concluded from very marked differences observed in the sedimentation–pH behavior of two GC-rich DNA's. An acid denaturation scheme for a GC-rich DNA segment is suggested. Reversibility of the acid denaturation is explained by the existence of stable, protonated, single GC base pairs in nonprotonated stacked single-stranded domains formed in the acid-induced transition region.
TL;DR: A sensitive assay system of Yaba virus was established in a cynomolgus monkey kidney cell line, JINET, in which the virus caused multilayered cellular foci countable even with the unaided eye.
Abstract: A sensitive assay system of Yaba virus (YV) was established in a cynomolgus monkey kidney cell line, JINET, in which the virus caused multilayered cellular foci countable even with the unaided eye. The specificity of the foci induced by YV in these cells was demonstrated by (1) the focus-forming ability was destroyed by heating at 60 C for 12 min; (2) the focus formation was inhibited by specific antiserum; (3) specific fluorescence was detected only in cells composing the foci when tested by fluorescent antibody technique; (4) a linear relationship was observed between the virus concentration and the number of foci formed; (5) YV preparation passed 20 times in JINET cells still possessed “tumorigenicity” in cynomolgus monkeys. The sensitivity of JINET cells to YV was comparable to that of cynomolgus monkeys, and YV was successively propagated in JINET cells with 2 log increase in infectivity titer during over 40 serial passages. Application of this assay system to growth kinetic studies of YV and quantitation of neutralizing antibody to YV is also discussed.
TL;DR: In this article, precipitation titration with tetraphenylarsonium chloride was used to determine perchlorate and tetrafluoroborate at low concentrations by using anionselective electrodes.
TL;DR: Spectrophotometric results show that thallium(III) can be quantitatively reduced to thallia(I) with oxalic acid in aqueous medium when heated to near boiling point.
TL;DR: Fluorine in organic materials is determined, after combustion in the Kirsten hot flask, by titration with lanthanum nitrate using the fluoride ion specific electrode as indicating electrode as discussed by the authors.
TL;DR: In this article, a kinetic and analytical study of the reaction of vanadium(IV) with potassium bromate is reported, and a possible mechanism is proposed for the reaction, which is found to obey the rate equation.
Abstract: A kinetic and analytical study of the reaction of vanadium(IV) with potassium bromate is reported. The kinetics were studied in perchloric acid media and the reaction was found to obey the rate equation [graphic omitted]. A value for k0 of 7·50 minute–1 was obtained at 20° C and an ionic strength of 0·10 M. Values for K1 of 88·8 lmole–1 and for the activation energy of 19 kcal. mole–1 were obtained, and a possible mechanism is proposed for the reaction.The determination of vanadium(IV) by photometric titration with potassium bromate is feasible at concentrations of vanadium(IV) down to 2 × 10–3M and at sulphuric acid concentrations above 0·06 M. An accuracy of ±0·5 per cent. is obtained for concentrations of vanadium(IV) between 5 and 10 × 10–3M. Under these acid conditions bromate acts as a five electron oxidant and bromine is a primary product of the reaction.
TL;DR: In this article, a rapid, precise, and accurate method for the determination of small amounts of thiourea and thioacetamide was described, and Bordeaux red was a suitable indicator when N -bromosuccinimide was used as direct titrant.
TL;DR: In this paper, a new solid-state cadmium ion selective electrode was evaluated and interference effects were considered and the electrode was used to detect the endpoint in titrations of the ion in water and in dimethyl sulfoxide.
Abstract: A new solid-state cadmium ion selective electrode is evaluated. Interference effects are considered and the electrode is used to detect the endpoint in titrations of cadmium ion in water and in dimethylsulfoxide.