scholarly journals The binding of cyanide to ferroperoxidase

1971 ◽  
Vol 122 (1) ◽  
pp. 79-87 ◽  
Author(s):  
Charles Phelps ◽  
Eraldo Antonini ◽  
Maurizio Brunori
Keyword(s):  
Sodium Dithionite ◽  
Affinity Constant ◽  
Kinetic Measurements ◽  
First Order ◽  
Ph Values ◽  
Cyanide Binding ◽  
Single Process ◽  
Ph Jump ◽  
Equilibrium And Kinetics ◽  
Kinetics Of

1. The equilibrium and kinetics of cyanide binding to ferroperoxidase were investigated. At pH9.1 the equilibrium and kinetic measurements agree closely and disclose a single process with an affinity constant of 1.1×103m@!-1 and combination and dissociation velocity constants of 29m-1·s-1 and 2.5×10-2s-1 respectively. 2. At pH values below 8 the affinity constant falls until at pH6.0 the ferroperoxidase·cyanide complex is no longer formed. This is shown to be associated with the formation of ferriperoxidase·cyanide complex in the mixture even in the presence of excess of sodium dithionite. 3. Rapid-pH-jump experiments show a fast pseudo-first-order interconversion between ferroperoxidase·cyanide complex at pH9.1 and ferriperoxidase·cyanide complex at pH6.0. 4. The kinetics of binding of cyanide to dithionite-reduced peroxidase at pH6.0 are complicated and radically different from those observed at pH9.1. 5. Above pH8 the change of affinity constant with pH is consistent with the undissociated species, HCN, being bound by the ferroperoxidase. The enthalpy for this process measured both by equilibrium and kinetic methods is about -8kcal/mol. 6. The binding of cyanide to reconstituted peroxidases, proto, meso and deutero, was investigated. 7. The results are discussed in relation to known data on cyanide binding to other haemoproteins.

scholarly journals The binding of ethyl isocyanide to ferroperoxidase

1972 ◽  
Vol 128 (2) ◽  
pp. 377-382 ◽  
Author(s):  
Charles Phelps ◽  
Eraldo Antonini ◽  
Maurizio Brunori
Keyword(s):  
Process Model ◽  
Dissociation Constants ◽  
Ph Dependence ◽  
Affinity Constant ◽  
Dependent Manner ◽  
Ph Values ◽  
Cyanide Binding ◽  
Equilibrium And Kinetics ◽  
Kinetics Of ◽  
A New Species

The equilibrium and kinetics of ethyl isocyanide binding to ferroperoxidase were studied. At pH9.1 the results of both studies are consistent with a single-process model with an affinity constant of 95m−1 and combination and dissociation constants of 2.2×103m−1·s−1 and 23s−1 respectively. Ethyl isocyanide is not bound significantly at pH values lower than 6.0, and in this behaviour and the pH-dependence of the affinity constant, similarities exist between isocyanide and cyanide binding. The enthalpy of the process measured by equilibrium methods is −59kJ/mol (−14kcal/mol). At pH values below 9, the ethyl isocyanide adduct changes in a slow time-dependent manner, giving rise to a new species. These changes are reversible on increasing the pH. The results are discussed in relation to other known information about ligand binding to ferroperoxidase and to myoglobin.

scholarly journals Kinetics of thiamin cleavage by sulphite

1969 ◽  
Vol 113 (4) ◽  
pp. 611-615 ◽  
Author(s):  
J. Leichter ◽  
M. A. Joslyn
Keyword(s):  
Aqueous Solutions ◽  
Rate Constant ◽  
Sulphur Dioxide ◽  
First Order ◽  
Ph Values ◽  
Rate Of Reaction ◽  
Kinetics Of

Results are presented on the rate of thiamin cleavage by sulphite in aqueous solutions as affected by temperature (20–70°), pH(2·5–7·0), and variation of the concentration of either thiamin (1–20μm) or sulphite (10–5000μm as sulphur dioxide). Plots of the logarithm of percentage of residual thiamin against time were found to be linear and cleavage thus was first-order with respect to thiamin. At pH5 the rate was also found to be proportional to the sulphite concentration. In the pH region 2·5–7·0 at 25° the rate constant was 50m−1hr.−1 at pH5·5–6·0, and decreased at higher or lower pH values. The rate of reaction increased between 20° and 70°, indicating a heat of activation of 13·6kcal./mole.

Equilibrium and Kinetics of the Extraction of Gallium(III) from Sodium Hydroxide Solutions with 7-Dodecenyl-8-quinolinol (Kelex 100)

1993 ◽  
Vol 58 (5) ◽  
pp. 1093-1102 ◽  
Author(s):  
Aleksandra A. Mitrovic ◽  
Slobodan K. Milonjic ◽  
Zoja E. Ilic ◽  
Radomir V. Stevanovic
Keyword(s):  
Sodium Hydroxide ◽  
Sodium Hydroxide Solution ◽  
Aqueous Sodium Hydroxide ◽  
Sodium Concentration ◽  
Extraction Kinetics ◽  
Aqueous Sodium Hydroxide Solution ◽  
Ph Values ◽  
Constant Ph ◽  
Equilibrium And Kinetics ◽  
Kinetics Of

The influence of hydroxide ions concentration of the aqueous sodium hydroxide solution, at constant sodium concentrations, on the gallium extraction with Kelex 100 was examined in the hydroxide concentration range from 0.02 to 0.5 mol dm-3. The percentage of extracted gallium increases from 51% to 98% within the investigated hydroxide concentration range. The influence of sodium concentrations (from 1 to 6 mol dm-3) on the gallium extraction was also studied at constant pH values. The decrease of extracted gallium is slight for the sodium concentration up to 3 mol dm-3, while for the higher ones it is pronounced. The extraction kinetics was studied using a mixer-type apparatus. The rate expression of the extraction reaction of gallium with Kellex 100, for both lower and higher hydroxide concentrations are ascertained.

scholarly journals Kinetics of aflatoxin B1 and G2 adsorption on Ca-clinoptilolite

2000 ◽  
Vol 65 (10) ◽  
pp. 715-723 ◽  
Author(s):  
Aleksandra Dakovic ◽  
Magdalena Tomasevic-Canovic ◽  
Vera Dondur ◽  
Aleksandra Vujakovic ◽  
Predrag Radosevic
Keyword(s):  
Adsorption Process ◽  
Order Reaction ◽  
Active Centers ◽  
Fast Reaction ◽  
First Order ◽  
Ph Values ◽  
Zero Order Reaction ◽  
Rate Method ◽  
Adsorption Rates ◽  
Kinetics Of

The kinetics of aflatoxins B1 and G2 adsorption on Ca-clinoptilolite at pH2 and 7, in aqueous electrolyte at 37?C were studied. For both aflatoxins, the adsorption process begins with a fast reaction whereby most of the toxin is adsorbed in the first few minutes. This fast process is followed by the significantly slower process of aflatoxin bonding at active centers of mineral adsorbent. The initial rate method showed that the fast adsorption process of aflatoxin ?1 and G2, at both pH values is a first order reaction, while the slow adsorption process of these aflatoxins is a zero order reaction. The adsorption indexes and adsorption rates for both examined toxins were pH dependent. In the investigated initial toxins concentration ranges (500-3000 ?g/dm3), high adsorption indexes were achieved (> 80 %).

scholarly journals Remediation of Crystal Violet Dye Aqueous Solution Using Agro Waste Based Activated Carbon: Equilibrium and Kinetics Studies

2020 ◽  
pp. 1-11
Author(s):  
Chukwunonso Chukwuzuloke Okoye ◽  
Okechukwu Dominic Onukwuli ◽  
Chinenye Faith Okey- Onyesolu ◽  
Ifeoma Amaoge Obiora- Okafo
Keyword(s):  
Aqueous Solution ◽  
Kinetic Data ◽  
Adsorption Process ◽  
Particle Diffusion ◽  
Type I ◽  
First Order ◽  
Equilibrium And Kinetics ◽  
Equilibrium Data ◽  
Intra Particle Diffusion ◽  
Kinetics Of

Remediation of crystal violet (CV) dye aqueous solution was attempted using acid activated raphia hookeri seeds (AARHS) as adsorbent. Adsorption equilibrium and kinetics of CV dye uptake onto AARHS were examined in series of experimental runs, and effects of contact time and initial CV dye concentrations were investigated at different solution temperatures (303 K, 313 K and 323 K). Equilibrium and kinetic data modeling of the adsorption process was performed using selected theoretical methods. Four different forms of Langmuir (type I, II, III and IV) and Freundlich isotherms were considered for fitting the equilibrium data while zero order, first order, pseudo-first order (PFO), second order, types I, II, III and IV pseudo-second order (PSO) and intra-particle diffusion models were selected to describe the kinetics of the adsorption process. Error functions including coefficient of determination (R2), root mean square error (RMSE), chi square (χ2) and average relative error (ARE) were employed to reveal model of best fit. Results obtained from error value computations show that the equilibrium data best followed Freundlich isotherm, which indicates multilayer adsorption of CV dye onto AARHS. The calculated Freundlich’s adsorption intensity values at different temperatures reveal the favourability of the adsorption process. PSO type I, II and IV best fitted the kinetic data compared to other investigated models. Intra-particle diffusion plots depict that the adsorption process of CV dye onto AARHS is a two-step process and also, intra-particle diffusion is not the only rate-limiting step.

scholarly journals Lampiran 4A Paper Degradasi paraquat (1,1'-dimetil-4,4'bipyridilium) dalam Lingkungan Tanah Desa Oematanunu Kecamatan Kupang Barat

2021 ◽  
Author(s):  
Philiphi de Rozari
Keyword(s):  
Rate Constant ◽  
Light Condition ◽  
Sodium Dithionite ◽  
Well Water ◽  
Time Interval ◽  
Water Medium ◽  
Dark Condition ◽  
First Order ◽  
Kinetics Of

In thus research, the kinetics of paraquat degradation in a medium of Oematnunu soil filtrate medium at two conditions, i. e. light condition and dark condition (on direct sunshine for 8 hours per day) has been studied. to study the effect of sunshine in paraquat degradation, it gas been carried out a paraquat degradation in medium of sterilized aquadest, sterilized well water, sterilized Oematnunu soil filtrate, medium without sterilization like, medium aquadest, medium well water and medium Oematnunu soil filtrate without sterilization. on certain time interval, the rest of paraquat was determined by UV-Vis spectrophotometry after being reduced with sodium dithionite at a maximum wavelength of 604 nm. the results indicated that sunshine increased the rate of paraquat degradation. paraquat degradation studied medium followed kinetics of the first order. the rate constant of paraquat in Oematnunu soil filtrate medium (0,06998 0,00336 /day). higher than that in medium without sterilization and anothers sterilization medium, as well as in well water medium (0,06217 0,00317 /day), aquadest medium (0,03458 0,00252 /day), for anothers sterilized medium as Oematnunu soil filtrate medium (0,06086 0,00285 /day), sterilized well water medium (0,04720 0,00182 /day) and sterilized aquadest medium (0,03472 0,00251 /day).

Rate of reaction of dithionite ion with oxygen in aqueous solution

1964 ◽  
Vol 19 (3) ◽  
pp. 522-525 ◽  
Author(s):  
J. A. Morello ◽  
Margot R. Craw ◽  
H. P. Constantine ◽  
R. E. Forster
Keyword(s):  
Aqueous Solution ◽  
Reaction Rate ◽  
Initial Rate ◽  
Sodium Dithionite ◽  
Zero Order ◽  
Flowing Liquid ◽  
First Order ◽  
Rate Of Reaction ◽  
Dithionite Ion ◽  
Kinetics Of

The rate of removal of oxygen from aqueous solution by sodium dithionite in 0.1 m sodium hydroxide was studied in a rapid-reaction apparatus using a membrane-covered polarographic cell to determine Po2 in the flowing liquid. The measurements were made at 37 C, so that the data would be applicable in studies of the kinetics of oxyhemoglobin in blood. The initial concentrations in the mixed reacting solution were between 8 x 10-5 m and 47.5 x 10-5 m for dithionite, and either 10 x 10-5 m or 47.8 x 10-5 m for O2. The reaction over the first 40 msec was found to be first order with respect to dithionite and zero order with respect to molecular oxygen. The initial rate constant was 42.5 ± sd 3.6 sec-1. oxygen reduction by dithionite; hemoglobin; deoxygenation rate; dithionite-oxygen reaction rate Submitted on June 17, 1963

scholarly journals THE KINETICS OF PENETRATION

1930 ◽  
Vol 13 (6) ◽  
pp. 695-713 ◽  
Author(s):  
A. G. Jacques ◽  
W. J. V. Osterhout
Keyword(s):  
Living Cells ◽  
Low Ph ◽  
External Concentration ◽  
Time Curve ◽  
Rate Of Penetration ◽  
Velocity Constant ◽  
First Order ◽  
Ph Values ◽  
Concentration Of Ions ◽  
Kinetics Of

The rate of penetration of CO2 into living cells of Valonia has been studied at high and low pH values. The time curve of penetration appears to be of the first order but with a "velocity constant" which falls off from the start. The evidence indicates little penetration of ions. This is shown by (a) the similarity of velocity "constants" at high and low pH values, (b) the rate of penetration, which remains constant as long as the external concentration of undissociated CO2 remains constant no matter how much the concentration of ions varies.

Deposition of Functionalized Polyethylenimine-Dye onto Cotton and Wool Fibres

2014 ◽  
Vol 18 (1) ◽  
pp. 36-49 ◽  
Author(s):  
A.G. Hassabo ◽  
A. Mendrek ◽  
C. Popescu ◽  
H. Keul ◽  
M. Möller
Keyword(s):  
Deposition Process ◽  
Good Alternative ◽  
Kinetics Of Adsorption ◽  
First Order ◽  
Ph Values ◽  
First Order Kinetics ◽  
Colour Strength ◽  
Equilibrium Data ◽  
Amine Groups ◽  
Kinetics Of

Functionalized polyethylenimine–dye (FPEI) is prepared by mixing branched polyethyleneimine (PEI), in which its primary amine groups are modified at different ratios with a quaternary ammonium coupler (QI), and reactive dyestuff (RD) (QI/RD = 0/100, 20/80, 40/60, 60/40 and 80/20 mole/mole %). The deposition of FPEI from an aqueous solution onto the surface of cotton and wool fibres is studied. The adsorption of a charged polymer from an aqueous medium by cotton and wool fibres is investigated at different pH values, and the uptake of colour on fibres is measured by Datacolor and UVVIS spectrophotometers. The study of the kinetics of adsorption shows that pseudo-first-order kinetics provide the best correlation of the experimental data. The equilibrium data indicate that the deposition process onto both cotton and wool follows the Langmuir isotherm. In terms of colour strength (K/S value) the coated fibres compare well with those dyed with a commercial dyestuff, C.I. Basic Red 51, which suggests that the coating is a good alternative to classical dyeing.

Sign in / Sign up

Export Citation Format

Share Document