Stability of NADPH: effect of various factors on the kinetics of degradation.

1986 ◽  
Vol 32 (2) ◽  
pp. 314-319 ◽  
Author(s):  
J T Wu ◽  
L H Wu ◽  
J A Knight
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Degradation Rate ◽  
Neutral Ph ◽  
Degradation Reactions ◽  
Hydronium Ion ◽  
Effects Of Ph ◽  
Reaction Orders ◽  
Kinetics Of Degradation ◽  
Kinetics Of

Abstract Seeking to minimize degradation of NADPH during storage, reagent preparation, and assays, we investigated the effects of pH, temperature, and ionic strength as well as the effects of phosphate and acetate. NADH was also included for comparison. Our results indicate that the rate of degradation of NADPH is proportional most importantly to temperature and concentrations of hydronium ion, but also to concentrations of phosphate and acetate. The degradation rate decreased with increasing ionic strength at neutral pH, but increased slightly at lower pH. NADPH generally is less stable than NADH under the same conditions. The reaction orders with respect to hydronium ion and anions were near 1 for NADH degradation reactions, about 0.5 for NADPH. Rate constants for NADH and NADPH differed more at higher pH and lower phosphate and acetate concentrations.

Kinetics of hydrolysis of peroxodisulphate ions in acidic medium to peroxomonosulphuric acid

1981 ◽  
Vol 46 (5) ◽  
pp. 1229-1236 ◽  
Author(s):  
Jan Balej ◽  
Milada Thumová
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Acidic Medium ◽  
Measured Data ◽  
Molar Ratios ◽  
Starting Solution ◽  
Kinetics Of Hydrolysis ◽  
Rate Of Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of

The rate of hydrolysis of S2O82- ions in acidic medium to peroxomonosulphuric acid was measured at 20 and 30 °C. The composition of the starting solution corresponded to the anolyte flowing out from an electrolyser for production of this acid or its ammonium salt at various degrees of conversion and starting molar ratios of sulphuric acid to ammonium sulphate. The measured data served to calculate the rate constants at both temperatures on the basis of the earlier proposed mechanism of the hydrolysis, and their dependence on the ionic strength was studied.

The Characteristics and Kinetic Equation of 4-CP Biodegradation by Fusarium sp. HJ01

2012 ◽  
Vol 554-556 ◽  
pp. 1925-1928 ◽  
Author(s):  
Ji Wu Li ◽  
Xiao Hong Zhu ◽  
Jun Ya Pan
Keyword(s):  
Carbon Source ◽  
Sole Carbon Source ◽  
Degradation Rate ◽  
Order Equation ◽  
First Order ◽  
Haldane Model ◽  
Effects Of Ph ◽  
Fusarium Sp ◽  
Ph Range ◽  
Kinetics Of

The stain of Fusarium sp. HJ01 used in 4-chlorophenol (4-CP) degradation was isolated in our laboratory. The effects of pH, temperature, 4-CP concentration, carbon source on 4-CP degradation rate were studied. It was concluded that Fusarium sp. HJ01 could grow with 4-CP as the sole carbon and energy source. 4-CP concentration of 100mg/L in the pH range of 4~10 and temperature range of 25°C~35°C could be degraded completely. The capacity of 4-CP degradation was effectively enhanced by the addiction of sucrose. The kinetics of 4-CP degradation could well accord with the Haldane model for 4-CP as the sole carbon source and with first order equation for added other sucrose.

Kinetics of iron(III) hydrolysis and precipitation in aqueous glycine solutions assessed by voltammetry

2009 ◽  
Vol 74 (10) ◽  
pp. 1531-1542 ◽  
Author(s):  
Vlado Cuculić ◽  
Ivanka Pižeta
Keyword(s):  
Ionic Strength ◽  
Complex Formation ◽  
Rate Constants ◽  
Glycine Concentration ◽  
First Order ◽  
Mercury Drop Electrode ◽  
Calculated Rate ◽  
Cathodic Voltammetry ◽  
Kinetics Of ◽  
Voltammetric Measurements

The kinetics of iron(III) hydrolysis and precipitation in aqueous glycine solutions were studied by cathodic voltammetry with a mercury drop electrode. The kinetics was controlled by changing ionic strength (I), pH and glycine concentration. Voltammetric measurements clearly showed formation and dissociation of a soluble Fe(III)–glycine complex, formation of iron(III) hydroxide and its precipitation. The rate constants of iron(III) hydroxide precipitation were assessed. The precipitation is first-order with respect to dissolved inorganic iron(III). The calculated rate constants of iron(III) precipitation varied from 0.18 × 10–5 s–1 (at 0.2 M total glycine, pH 7.30, I = 0.6 mol dm–3) to 2.22 × 10–3 s–1 (at 0.1 M total glycine, pH 7.30, I = 0.2 mol dm–3). At 0.5 M total glycine and I = 0.6 mol dm–3, the iron(III) precipitation was not observed.

Carbohydrates in alkaline systems. II. Kinetics of the transformation and degradation reactions of cellobiose, cellobiulose, and 4-O-β-D-glucopyranosyl-D-mannose in 1 M sodium hydroxide at 22 °C

1969 ◽  
Vol 47 (21) ◽  
pp. 3957-3964 ◽  
Author(s):  
Donald J. MacLaurin ◽  
John W. Green
Keyword(s):  
Sulfuric Acid ◽  
Sodium Hydroxide ◽  
Column Chromatography ◽  
Rate Constants ◽  
Reaction Rate ◽  
Reaction System ◽  
Reaction Rate Constants ◽  
Degradation Reactions ◽  
Fructose 2 ◽  
Kinetics Of

Rates of isomerization, epimerization, and degradation reactions were measured for cellobiose (7), cellobiulose (8), and 4-O-β-D-glucopyranosyl-D-mannose (9) at 0.001 M in 1 M NaOH under N2 in the dark at 22 °C. Reaction system resolution was by column chromatography on anion resins in the borate form. Assay for D-glucose (1), D-fructose (2), D-mannose (3), and 7,8, and 9 was by continuous automated colorimetry of column effluent with orcinol–sulfuric acid as reagent. Reaction rate constants (h−1) found: k78 0.078, k79 0.0005, k7,10 0.002, k87 0.022, k89 0.003 k81 0.065, k8,12 0.023, k97 0.002, k98 0.013, k9,11 0.006 where 10,11, and 12 are other products than 1,2,3,7,8, and 9. Details for preparation of 8 and 9 are given.

KINETICS OF THE OXIDATION OF URANIUM (IV) BY IRON (III) IN AQUEOUS SOLUTIONS OF PERCHLORIC ACID

1955 ◽  
Vol 33 (12) ◽  
pp. 1780-1791 ◽  
Author(s):  
R. H. Betts
Keyword(s):  
Electron Transfer ◽  
Ionic Strength ◽  
Aqueous Solutions ◽  
Perchloric Acid ◽  
Rate Constants ◽  
Kcal Mole ◽  
Kinetics Of Oxidation ◽  
Temperature Coefficients ◽  
Kinetics Of ◽  
Rate Controlling Step

The kinetics of oxidation of uranium (IV) by iron (III) in aqueous solutions of perchloric acid have been investigated at four temperatures between 3.1 °C. and 24.8 °C. The reaction was followed by measurement of the amount of ferrous ion formed. For the conditions (H+) = 0.1–1.0 M, ionic strength = 1.02, (FeIII) = 10−4–10−5 M, and (UIV) = 10−4–10−5 M, the observed rate law is d(Fe2+)/dt = −2d(UIV)/dt[Formula: see text]K1 and K2 are the first hydrolysis constants for Fe3+ and U4+, respectively, and K′ and K″ are pseudo rate constants. At 24.8 °C., K′ = 2.98 sec.−1, and K″ = 10.6 mole liter−1 sec−1. The corresponding temperature coefficients are ΔH′ = 22.5 kcal./mole and ΔH″ = 24.2 kcal./mole. The kinetics of the process are consistent with a mechanism which involves, as a rate-controlling step, electron transfer between hydrolyzed ions.

Kinetics of oxidation of reduced cytochrome c by aquacopper(II) and chlorocopper(II) complexes in the presence of oxygen

1981 ◽  
Vol 34 (1) ◽  
pp. 99 ◽  
Author(s):  
JK Yandell
Keyword(s):  
Reaction Mechanism ◽  
Ionic Strength ◽  
Cytochrome C ◽  
Rate Constants ◽  
Kinetics Of Oxidation ◽  
Ferrocytochrome C ◽  
Kinetics Of

The rate constants for the oxidation of reduced cytochrome c by aquacopper(II) ion, aquachloro- copper(II) ion and aquadichlorocopper(II) were found to be 5.7�0.3 1. mol-1 s-1, 2.3×102 1. mol-1 s-1 and 5.6xl031. mol-1 s-1 respectively at 25�C, ionic strength 0.1 and pH 4.0. At low ratios of aquacopper(II) ion to ferrocytochrome c, when oxygen is required to completely oxidize the cytochrome, the reaction mechanism was found to be complex. No evidence for the involvement of copper bound to the cytochrome was found.

Kinetics of oxidation of cis-bis(ethylenediamine)isothiocyanatonitrocobalt(III) ion with peroxodisulphate

1979 ◽  
Vol 44 (12) ◽  
pp. 3588-3594 ◽  
Author(s):  
Vladislav Holba ◽  
Olga Volárová
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Oxidation Kinetics ◽  
Reaction Rate ◽  
Salt Effect ◽  
Activation Parameters ◽  
Reaction Products ◽  
Kinetics Of Oxidation ◽  
Thermodynamic Activation Parameters ◽  
Kinetics Of

The oxidation kinetics of cis-bis(ethylenediamine)isothiocyanonitrocobalt(III) ion with peroxodisulphate was investigated in the medium of 0.01 M-HClO4 in dependence on the ionic strength and temperature and the reaction products were identified. Extrapolated values of thermodynamic activation parameters were determined from the temperature dependence of the rate constants extrapolated to zero ionic strength. The distance of the closest approach was estimated for the reacting ions by evaluating the primary salt effect. To elucidate the mechanism, the influence of the cyclic polyether 18-crown-6 on the reaction rate was followed.

Carbohydrates in alkaline systems. I. Kinetics of the transformation and degradation of D-glucose, D-fructose, and D-mannose in 1 M sodium hydroxide at 22 °C

1969 ◽  
Vol 47 (21) ◽  
pp. 3947-3955 ◽  
Author(s):  
Donald J. MacLaurin ◽  
John W. Green
Keyword(s):  
Sulfuric Acid ◽  
Sodium Hydroxide ◽  
Column Chromatography ◽  
Rate Constants ◽  
Reaction Rate ◽  
Reaction System ◽  
Reaction Rate Constants ◽  
Degradation Reactions ◽  
Fructose 2 ◽  
Kinetics Of

Rates of isomerization, epimerization, and degradation reactions were measured for D-glucose (1), D-fructose (2), and D-mannose (3) at 0.002 M in 1 M NaOH under N2 in the dark at 22 °C. Reaction system resolution was by column chromatography on anion resins in the borate form. Assay for 1, 2, and 3 was by continuous automated colorimetry of column effluent using orcinol/sulfuric acid as a reagent. D-Allose and D-altrose were not detected. Reaction rate constants (h−1) found: k12 0.038, k13 0.0005, k15 0.002, k21 0.036, k23 0.006, k24 0.072, k31 0.0005, k32 0.011, k36 0.002, where 4, 5, and 6 are products formed from 1, 2, or 3, respectively.

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