scholarly journals Pig heart fumarase really does exhibit negative kinetic co-operativity at a constant ionic strength

1986 ◽  
Vol 235 (3) ◽  
pp. 891-893 ◽  
Author(s):  
B B Hasinoff ◽  
J P Davey
Keyword(s):  
Ionic Strength ◽  
Constant Ionic Strength ◽  
Buffer Concentration ◽  
Ph Buffer ◽  
Kinetics Of

The kinetics of the action of fumarase on L-malate and fumarate were investigated at constant ionic strength. This was done to evaluate reports that fumarase follows simple Michaelis-Menten kinetics. However, when pH, buffer concentration and ionic strength are all maintained at constant values, the Lineweaver-Burk plots exhibit pronounced downward curvature, characteristic of negative kinetic co-operativity.

Kinetics and Mechanism of Hexachloroiridate(IV) Oxidation of Arsenic(III) in Acidic Perchlorate Solutions

1992 ◽  
Vol 57 (7) ◽  
pp. 1451-1458 ◽  
Author(s):  
Refat M. Hassan
Keyword(s):  
Ionic Strength ◽  
Fractional Order ◽  
Activation Parameters ◽  
Order Reaction ◽  
First Order Reaction ◽  
Intermediate Complex ◽  
Constant Ionic Strength ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Kinetics Of

The kinetics of oxidation of arsenic(III) by hexachloroiridate(IV) at lower acid concentrations and at constant ionic strength of 1.0 mol dm-3 have been investigated spectrophotometrically. A first-order reaction in [IrCl62-] and fractional order with respect to arsenic(III) have been observed. A kinetic evidence for the formation of an intermediate complex between the hydrolyzed arsenic(III) species and the oxidant was presented. The results showed that decreasing the [H+] is accompanied by an appreciable acceleration of the rate of oxidation. The activation parameters have been evaluated and a mechanism consistent with the kinetic results was suggested.

scholarly journals Fluorimetric studies on the dimerization equilibrium of protoporphyrin IX and its haemato derivative

1983 ◽  
Vol 209 (2) ◽  
pp. 547-552 ◽  
Author(s):  
R Margalit ◽  
N Shaklai ◽  
S Cohen
Keyword(s):  
Ionic Strength ◽  
Fluorescence Quenching ◽  
Fluorescence Intensity ◽  
Salt Concentration ◽  
Equilibrium Constants ◽  
Protoporphyrin Ix ◽  
Constant Ionic Strength ◽  
Aggregation Process ◽  
Buffer Concentration ◽  
Common Anion

The aggregations of protoporphyrin IX and haematoporphyrin IX in aqueous solutions were studied by fluorimetric techniques. Porphyrin concentrations were limited to 0.001-0.1 microM and 0.01-1 microM for protoporphyrin and haematoporphyrin respectively, where dimerization is the dominant aggregation process. The dimerization equilibrium constants (at 25 degrees C, neutral pH, 50 mM-Tris/HCl buffer) were determined to be 3×10(7) M and 4×10(5) M for the proto and the haemato derivatives respectively. The fluorescence intensity of a given protoporphyrin solution (within the range indicated above) was markedly decreased by salts in the system, over the salt concentration range 0.1-7 mM at constant ionic strength, in the sequence CaCl2 greater than MgCl2 greater than KCl greater than NaCl. The direction of this effect, fluorescence quenching, suggests that these salts promote an increase in aggregation. The differences in the magnitudes of the effect, among different salt species sharing a common anion, at constant ionic strength, imply that the effect is cation-specific. In contrast, the fluorescence intensity of a given solution of haematoporphyrin (within the range indicated above) was unaffected by these salts, under similar concentrations, nor was it sensitive to the total buffer concentration, or to the type of buffer in the system.

Oxidation of (+)-(R)-Pantothenic Acid by Aqueous Alkaline Potassium Permanganate: A Kinetic and Mechanistic Approach

2002 ◽  
Vol 216 (6) ◽  
Author(s):  
S.M. Desai ◽  
N.N. Halligudi ◽  
S.K. Mavalangi ◽  
S.T. Nandibewoor
Keyword(s):  
Ionic Strength ◽  
Potassium Permanganate ◽  
Alkaline Medium ◽  
Pantothenic Acid ◽  
Constant Ionic Strength ◽  
Aqueous Alkaline Medium ◽  
Kinetics Of Oxidation ◽  
Mechanistic Approach ◽  
Kinetics Of

The kinetics of oxidation of (+)-(R)-pantothenic acid (PA) by permanganate in aqueous alkaline medium at constant ionic strength 0.20 mol dm

Ligand substitution reaction on a platinum(ii) complex with bio-relevant thiols: kinetics, mechanism and bioactivity in aqueous medium

RSC Advances ◽  
2014 ◽  
Vol 4 (82) ◽  
pp. 43516-43524 ◽  
Author(s):  
Avradeep Samanta ◽  
Goutam Kr. Ghosh ◽  
Ishani Mitra ◽  
Subhajit Mukherjee ◽  
Jagadeesh C. Bose K ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Aqueous Medium ◽  
Substitution Reaction ◽  
Ligand Substitution ◽  
Constant Ionic Strength ◽  
Kinetics Of ◽  
Ligand Substitution Reaction

Kinetics of the interaction between [Pt(pic)(H2O)2](ClO4)2and selected thiols has been studied in aqueous medium as a function of [complex], [thiol], pH and temperature at constant ionic strength.

Kinetics and Mechanism of Ligand Substitutionin Triglycinatovanadium(III) by EDTA and NTA in Aqueous Solutions

1994 ◽  
Vol 59 (5) ◽  
pp. 1077-1085
Author(s):  
Yasuhisa Ikeda ◽  
Refat M. Hassan ◽  
Moustafa M. Abd El-Fattah ◽  
Yul Y. Park ◽  
Hiroshi Tomiyasu
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Kinetic Parameters ◽  
Ligand Substitution ◽  
Reactive Species ◽  
Constant Ionic Strength ◽  
Substitution Reactions ◽  
First Order ◽  
Kinetics Of ◽  
Mechanism Of The Reaction

The kinetics of ligand substitution reactions in triglycinatovanadium(III) by EDTA and NTA as multidentate ligands were investigated at a constant ionic strength of 2.5 mol dm-3 spectrophotometrically. The substitutions were second-order reactions, first order in both reactants. Their rate could be expressed in the form r = k [V(gly)3] [EDTA(NTA)] where k = 2.62 .10-2 and 6.96 .10-2 mol-1 dm3 s-1 at 25 °C for EDTA and NTA, respectively. The results obtained at different pH indicated that [H2edta]2- and [Hnta]2- ions were the most reactive species in the substitution. Kinetic parameters have been evaluated and a tentative mechanism of the reaction has been proposed.

Kinetics and mechanism of oxidation of Chitosan Polysaccharide by Permanganate Ion in Aqueous Perchlorate Solutions

2003 ◽  
Vol 2003 (4) ◽  
pp. 182-183 ◽  
Author(s):  
Gamal Abdel-Whab Ahmed ◽  
Khalid Suliman Khairou ◽  
Refat Moustafa Hassan
Keyword(s):  
Ionic Strength ◽  
Second Order ◽  
Kinetics And Mechanism ◽  
Constant Ionic Strength ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Mechanism Of Oxidation ◽  
Kinetics Of ◽  
Overall Kinetics ◽  
Permanganate Ion

The kinetics of oxidation of chitosan as polysaccharide by permanganate in aqueous perchlorate media at a constant ionic strength was found to have second-order overall kinetics and to be first-order in the concentration of both reactants, the results obtained showed that the reaction is acid catalysed.

Adsorption of chlorate and bromate ions on mercury electrodes from constant ionic strength solutions

1988 ◽  
Vol 85 ◽  
pp. 523-527
Author(s):  
M.M. Zuleika ◽  
Palhares SILVA ◽  
Ernesto Rafael GONZALEZ ◽  
Luis Alberto AVACA ◽  
Artur de Jesus MOTHEO
Keyword(s):  
Ionic Strength ◽  
Constant Ionic Strength ◽  
Mercury Electrodes

Study of the Cu(II) removal from aqueous solutions by adsorption on titania

2013 ◽  
Vol 12 (3) ◽  
pp. 239-247
Keyword(s):  
Heavy Metals ◽  
Ionic Strength ◽  
Toxic Metals ◽  
Low Cost ◽  
Lateral Interaction ◽  
Tio2 Surface ◽  
High Toxicity ◽  
Removal Of Heavy Metals ◽  
Solution Parameters ◽  
Kinetics Of

The removal of heavy metals from wastewaters is a matter of paramount importance due to the fact that their high toxicity causes major environmental pollution problems. One of the most efficient, applicable and low cost methods for the removal of toxic metals from aqueous solutions is that of their adsorption on an inorganic adsorbent. In order to achieve high efficiency, it is important to understand the influence of the solution parameters on the extent of the adsorption, as well as the kinetics of the adsorption. In the present work, the adsorption of Cu(II) species onto TiO2 surface was studied. It was found that the adsorption is a rapid process and it is not affected by the value of ionic strength. In addition, it was found that by increasing the pH, the adsorbed amount of Cu2+ ions and the value of the adsorption constant increase, whereas the value of the lateral interaction energy decreases.

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