Basicity of the thionamide group of α-aminothionamides. Attenuation of electrostatic effects by solvation

1986 ◽  
Vol 64 (12) ◽  
pp. 2310-2314
Author(s):  
Martino Paventi ◽  
Fenton Heirtzler ◽  
John T. Edward
Keyword(s):  
Ionic Strength ◽  
Dissociation Constants ◽  
High Ionic Strength ◽  
Amide Group ◽  
Electrostatic Effects ◽  
Ammonium Group ◽  
Group A ◽  
Electrostatic Theory

The first dissociation constants pK1of four diprotonated α-aminothionamides, determined spectrophotometrically, are between −8.1 to −8.8; the second dissociation constants pK2, of three of these compounds, determined titrimetrically, are between 7.3 and 7.7. Both pK1and pK2 values are close to those calculated from current electrostatic theory for equilibria in solutions of zero ionic strength, in spite of the fact that data for pK1values were obtained in solutions of high ionic strength. Results indicate a much larger effect of the charged ammonium group on the basicity of the thionamide group than on the basicity of the amide group. A possible explanation based on the greater hydration of the protonated amide group is advanced.

Determination of Co(II) and Ni(II)-humate stability constants at high ionic strength NaCl solutions

2000 ◽  
Vol 88 (9-11) ◽  
Author(s):  
D.N. Kurk ◽  
Gregory R. Choppin
Keyword(s):  
Humic Acid ◽  
Ionic Strength ◽  
Solvent Extraction ◽  
Potentiometric Titration ◽  
Stability Constants ◽  
Dissociation Constants ◽  
High Ionic Strength ◽  
Extraction Technique ◽  
Solvent Extraction Technique

Complexation of Ni(II) and Co(II) by unfractionated humic acid (HA) was measured in 0.3 to 5.0 m NaCl solutions at pH 6 and 20 °C, using a solvent extraction technique. The dissociation constants and capacities of the humic acid were investigated in 0.1 to 5.0 m NaCl solutions at 25 °C using potentiometric titration methods.

Thermodynamics and dissociation constants of carboxylic acids at high ionic strength and temperature

2007 ◽  
Vol 360 (12) ◽  
pp. 3671-3680 ◽  
Author(s):  
P. Thakur ◽  
J.N. Mathur ◽  
R.C. Moore ◽  
G.R. Choppin
Keyword(s):  
Ionic Strength ◽  
Carboxylic Acids ◽  
Dissociation Constants ◽  
High Ionic Strength

scholarly journals The distribution of blood-group antigens on butanol extraction of human erythrocyte ‘ghosts’

1974 ◽  
Vol 138 (3) ◽  
pp. 381-386 ◽  
Author(s):  
D. J. Anstee ◽  
M. J. A. Tanner
Keyword(s):  
Ionic Strength ◽  
Blood Group ◽  
Aqueous Phase ◽  
High Ionic Strength ◽  
High Yield ◽  
Erythrocyte Ghosts ◽  
Blood Group A ◽  
Butanol Extraction ◽  
Group A ◽  
Blood Group P

The distribution of protein and blood-group-antigen activity obtained after butanol extraction of erythrocyte `ghosts' under various conditions is described. Butanol extraction under low-ionic strength conditions results in the recovery of membrane protein in high yield in the aqueous phase. Blood-group-A activity is found in both the aqueous and butanol phases, whereas blood-group-P activity is confined to the butanol phase and blood-group-I and blood-group-MN activity are restricted to the aqueous phase. Much lower yields of protein are obtained in the aqueous phase when high-ionic-strength conditions are used. An appreciable amount of material is precipitated at the interface. Under these conditions blood-group-P activity is found only in the butanol phase, blood group-A activity in the butanol phase and interface material and only blood-group-MN activity in the aqueous phase. In contrast with previous reports no correlation could be demonstrated between the secretor status of the donors and the presence of blood-group-A activity in the aqueous phase after butanol extraction under any of the extraction conditions used. By using butanol extraction under high-ionic-strength conditions it is possible to isolate the blood-group-MN-active sialoglycoprotein in high yield from erythrocyte `ghosts' by a simple procedure.

The Reactivity of the N-terminal Isoleucine of α-Chymotrypsin as a Function of Ionic Strength

1971 ◽  
Vol 49 (5) ◽  
pp. 529-534 ◽  
Author(s):  
A. Kurosky ◽  
J. E. S. Graham ◽  
Joan W. Dixon ◽  
T. Hofmann
Keyword(s):  
Ionic Strength ◽  
Nitrous Acid ◽  
High Ionic Strength ◽  
Amino Group ◽  
Model Compounds ◽  
Third Order ◽  
X Ray ◽  
A Value ◽  
Group A ◽  
Low Ionic Strength

The reactivity of the α-amino group of isoleucine-16 of α-chymotrypsin towards nitrous acid at pH 4.0 and 0° is strongly dependent on ionic strength. Third-order deamination rate constants at low ionic strength (μ = 0.1 M) are 500–1000 times higher than those at high ionic strength (μ = 5.0 and 6.0 M) and are independent of the nature of the ions and the chymotrypsin concentration. Extrapolation to zero ionic strength of a plot of the logarithms of the constants against ionic strength leads to a value which is the same as that for the exposed α-amino group of the model compounds isoleucylvaline and valylvaline, and of the N-terminal isoleucine of pepsin. The deamination rate constant of the dipeptide valylvaline varies only two- to three-fold between ionic strength of 0.1 M and 6 M. The results suggest that the concept of a "buried" N-terminal as shown by X-ray analysis (carried out at pH 4.2 and ionic strength 9–11 M) requires modification; at low ionic strength (0.1 M) the reactivity of the N-terminal is only little below that of an exposed amino group, a fact which suggests that the amino group is much more available than shown by the X-ray analysis. The results are interpreted in terms of an effect of the ionic strength on the equilibrium between two conformational states of the enzyme.

Importance of Protease Inhibition in Studies on Purified Factor VIII (Antihaemophilic Factor)

1976 ◽  
Vol 35 (01) ◽  
pp. 186-190 ◽  
Author(s):  
Eugen A. Beck ◽  
Peter Bachmann ◽  
Peter Barbier ◽  
Miha Furlan
Keyword(s):  
Ionic Strength ◽  
Factor Viii ◽  
Gel Filtration ◽  
High Ionic Strength ◽  
Procoagulant Activity ◽  
Carrier Protein ◽  
Protease Inhibition ◽  
Functional Sites ◽  
Molecular Weight Peak ◽  
Von Willebrand

SummaryAccording to some authors factor VIII procoagulant activity may be dissociable from carrier protein (MW~ 2 × 106) by agarose gel filtration, e.g. at high ionic strength. We were able to reproduce this phenomenon. However, addition of protease inhibitor (Trasylol) prevented the appearance of low molecular weight peak of factor VIII procoagulant activity both at high ionic strength and elevated temperature (37°C). We conclude from our results that procoagulant activity and carrier protein (von Willebrand factor, factor VIII antigen) are closely associated functional sites of native factor VIII macro molecule. Consequently, proteolytic degradation should be avoided in functional and structural studies on factor VIII and especially in preparing factor VIII concentrate for therapeutic use.

THE RELATIVE DISTRIBUTION OF THYROXINE, TRIIODOTHYRONINE AND 3,3′,5′-(REVERSE)-TRIIODOTHYRONINE IN VARIOUS FRACTIONS OF THYROGLOBULIN

1978 ◽  
Vol 88 (2) ◽  
pp. 298-305 ◽  
Author(s):  
Peter Laurberg
Keyword(s):  
Ionic Strength ◽  
Guinea Pig ◽  
Sucrose Gradient ◽  
Deae Cellulose ◽  
High Ionic Strength ◽  
Relative Distribution ◽  
Thyroid Extract ◽  
Reverse Triiodothyronine ◽  
Thyroid Secretion ◽  
Stable Iodine

ABSTRACT Thyroglobulin fractions rich and poor in new thyroglobulin were separated by means of DEAE-cellulose chromatography of dog thyroid extracts and by zonal ultracentrifugation in a sucrose gradient of guinea pig thyroid extract incubated at low temperature. The distribution of thyroxine, triiodothyronine and 3,3′,5′-(reverse)-triiodothyronine in hydrolysates of the different fractions was estimated by radioimmunoassays. Following DEAE-cellulose chromatography there was a small but statistically significant increase in the T4/T3 ratio in thyroglobulin fractions eluted at high ionic strength - that is fractions relatively rich in stable iodine but poor in fresh thyroglobulin. There were no differences in the T4/rT3 ratios between the different fractions. The ratios between iodothyronines were almost identical in the various thyroglobulin fractions following zonal ultracentrifugation in a sucrose gradient of cold treated guinea pig thyroid extract. These findings lend no support to the possibility that a relatively high content of triiodothyronines in freshly synthesized thyroglobulin modulates the thyroid secretion towards a preferential secretion of triiodothyronine and 3,3′,5′-(reverse)-triiodothyronine at the expense of the secretion of thyroxine.

Extraction of hafnium by means of some substituted 1-phenyl-3-methyl-4-benzoyl-pyrazol-5-ones

1981 ◽  
Vol 46 (8) ◽  
pp. 1901-1905 ◽  
Author(s):  
Oldřich Navrátil ◽  
Jiří Smola
Keyword(s):  
Ionic Strength ◽  
Aqueous Phase ◽  
Dissociation Constants ◽  
Parent Substance ◽  
Benzoyl Group ◽  
Extraction Constants ◽  
Extraction Parameters ◽  
Substituted 1

Distribution between aqueous phase and benzene or chloroform was studied for 1-phenyl-3-methyl-4-benzoylpyrazol-5-ones with 2-chloro, 4-methoxy, 3-nitro, and 4-nitro substitution in the benzoyl group (ionic strength of the aqueous phase 0.1) and for hafnium in their presence (ionic strength 2.0). The distribution and dissociation constants of the reagents and the extraction constants of their hafnium complexes were determined. Hafnium was found to be extracted as the HfA4 species. The extraction parameters of the derivatives in question do not differ substantially from those of the parent substance.

scholarly journals Kaolin based protective barrier in municipal landfills against adverse chemo-mechanical loadings

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Partha Das ◽  
Tadikonda Venkata Bharat
Keyword(s):  
Ionic Strength ◽  
High Ionic Strength ◽  
The Self ◽  
Design Parameters ◽  
Layered System ◽  
Geosynthetic Clay Liners ◽  
Clay Liners ◽  
Landfill Liner ◽  
First Time ◽  
Applied Stresses

AbstractIn this work, we assess the self-sealing and swelling ability of the compacted granular bentonite (GB) under an inorganic salt environment and induced overburden stresses from the landfill waste. The laboratory permeation tests with high ionic strength salt solutions reveal that the GB fails to seal and exhibits a significant mechanical collapse under different applied stresses. The applicability of GB in the form of geosynthetic clay liners as the bottom liner facilities in landfills that produce high ionic strength salt leachates, therefore, remains a serious concern. We propose an additional barrier system based on kaolin, for the first time, to address this problem. The proposed kaolin-GB layered system performs satisfactorily in terms of its sealing and swelling ability even in adverse saline conditions and low overburden stresses. The kaolin improves the osmotic efficiency of the self and also helps the underlying GB layer to seal the inter-granular voids. The estimated design parameters by through-diffusion test suggest that the kaolin-GB layered system effectively attenuates the permeant flux and suitable as a landfill liner.

scholarly journals High ionic strength dissociation assay (HISDA) for high drug tolerant immunogenicity testing

Bioanalysis ◽  
2020 ◽  
Author(s):  
Gregor Jordan ◽  
Alexander Pöhler ◽  
Florence Guilhot ◽  
Meike Zaspel ◽  
Roland F Staack
Keyword(s):  
Ionic Strength ◽  
Acid Treatment ◽  
Structural Integrity ◽  
Drug Tolerance ◽  
High Ionic Strength ◽  
Acid Dissociation ◽  
High Drug ◽  
Overnight Incubation ◽  
Antidrug Antibody ◽  
High Doses

Aim: Antidrug antibody (ADA) assessment may be challenged in studies that involve the administration of high doses of biotherapeutics and/or with long half-lives. In such cases, ADA assays with optimized drug tolerance are desired. Material & Methods: We evaluated the use of MgCl2 to develop high ionic strength dissociation assays in two investigational examples (bridging enzyme-linked immunosorbent ADA assays) to attain high drug tolerance while maintaining best possible structural integrity of ADAs. Results: Both ADA-bridging assays treated with MgCl2 showed improved drug tolerance and higher signal-to-blank values compared with overnight incubation or acid treatment. Conclusion: The use of MgCl2 treatment in ADA-bridging assays provides a sensitive, drug tolerant and easy-to-use alternative in cases where acid dissociation is not possible or unwanted.

scholarly journals High salt compatible oxyanion receptors by dual ion imprinting

2020 ◽  
Vol 11 (16) ◽  
pp. 4246-4250 ◽  
Author(s):  
Sudhirkumar Shinde ◽  
Mona Mansour ◽  
Anil Incel ◽  
Liliia Mavliutova ◽  
Celina Wierzbicka ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Ion Pair ◽  
High Ionic Strength ◽  
High Salt ◽  
Ion Uptake ◽  
Ion Imprinting

Imprinting of an ion-pair in presence of mutually compatible anion and cation host monomers leads to polymers showing enhanced ion uptake in competitive high ionic strength buffers.

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