pH Dependence and Structural Interpretation of the Reactions ofCoprinus cinereusPeroxidase with Hydrogen Peroxide, Ferulic Acid, and 2,2‘-Azinobis(3-ethylbenzthiazoline-6-sulfonic acid)†

Biochemistry ◽  
1997 ◽  
Vol 36 (31) ◽  
pp. 9453-9463 ◽  
Author(s):  
A. Katrine Abelskov ◽  
Andrew T. Smith ◽  
Christine Bruun Rasmussen ◽  
H. Brian Dunford ◽  
Karen G. Welinder
Keyword(s):  
Hydrogen Peroxide ◽  
Ferulic Acid ◽  
Sulfonic Acid ◽  
Ph Dependence ◽  
Structural Interpretation

Сrude Plant Extracts Mediated Polyphenol Oxidation Reactions in the Presence of 3-Methyl-2-Benzothiazolinone Hydrazone for the Determination of Total Polyphenol Content in Beverages

2018 ◽  
Vol 15 (1) ◽  
pp. 11-20 ◽  
Author(s):  
Maria A. Morosanova ◽  
Anton S. Fedorov ◽  
Elena I. Morosanova
Keyword(s):  
Hydrogen Peroxide ◽  
Ferulic Acid ◽  
Gallic Acid ◽  
Caffeic Acid ◽  
Crude Extract ◽  
Reaction Rates ◽  
Green Bean ◽  
Polyphenol Content ◽  
Total Polyphenol ◽  
Total Polyphenol Content

Background: The consumption of antioxidants, including phenolic compounds, is considered important for preventing the oxidative damage diseases and ageing. The total polyphenol content (TPC) is the parameter used to estimate the quality of plant-derived products. Methods: Phenol oxidase activity of green bean (Phaseolus vulgaris) crude extract (in the presence of hydrogen peroxide) and banana (Musa sp.) pulp crude extract has been studied spectrophotometrically using catechol, gallic acid, caffeic acid, ferulic acid, and quercetin as substrates. All studied compounds have been oxidized in the presence of green bean crude extract and hydrogen peroxide; all studied compounds except ferulic acid have been oxidized in the presence of banana pulp crude extract. Michaelis constants (Km) and maximum reaction rates (Vmax) have been determined for oxidation in the presence of green bean crude extract and hydrogen peroxide (Km are 3.8×10-4 M, 1.6×10-3 M, 2.2×10-4 M, 2.3×10-4 M, 1.4×10-4 M and Vmax are 0.046 min-1, 0.102 min-1, 0.185 min-1, 0.053 min-1, 0.041 min-1 for catechol, gallic acid, caffeic acid, ferulic acid, and quercetin, respectively) and for oxidation in the presence of banana pulp crude extract (Km are 1.6×10-3 M, 3.8×10-3 M, 2.2×10-3 M, 4.2×10-4 M and Vmax are 0.058 min-1, 0.025 min-1, 0.027 min-1, 0.015 min-1 for catechol, gallic acid, caffeic acid, and quercetin, respectively). The influence of 3-methyl-2-benzothiazolinone hydrazone (MBTH) on the oxidation reactions kinetics has been studied: Michaelis constants values decrease and maximum reaction rates increase, which contributes to the increase in sensitivity of the determination. Results: Kinetic procedures of Total Polyphenol Content (TPC) determination using crude plants extracts in the presence of MBTH have been proposed (time of analysis is 1 min). For gallic acid (used as a standard for TPC determination) detection limit is 5.3×10-5 M, quantitation limit is 1.8×10-4 M, and linear range is 1.8×10-4 - 1.3×10-3 M for green bean crude extract; detection limit is 2.9×10-5 M, quantitation limit is 9.5×10-5 M, and linear range is 9.5×10-5 - 2.4×10-3 M for banana pulp crude extract. Proposed procedures are characterized by higher interference thresholds for sulfites, ascorbic acid, and citric acid compared to pure enzymes (horseradish peroxidase and mushroom tyrosinase) in the same conditions. Compared with standard Folin-Ciocalteu (FC) method the procedures described in this work are also characterized by less interference and more rapid determination. Conclusion: The procedures have been applied to TPC determination in tea, coffee, and wine samples. The results agree with the FC method for tea and coffee samples and are lower for wine samples, probably, due to sulfites interference.

ChemInform Abstract: Sulfonic Acid Resin-Catalyzed Oxidation of Aldehydes to Carboxylic Acids by Hydrogen Peroxide.

ChemInform ◽  
2013 ◽  
Vol 44 (29) ◽  
pp. no-no
Author(s):  
Xiaomei Yang ◽  
Si Tang ◽  
Tianliang Lu ◽  
Chen Chen ◽  
Lipeng Zhou ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Carboxylic Acids ◽  
Sulfonic Acid ◽  
Acid Resin ◽  
Catalyzed Oxidation ◽  
Sulfonic Acid Resin

The reduction of I2 by H2O2 in aqueous solution

2001 ◽  
Vol 79 (3) ◽  
pp. 304-311 ◽  
Author(s):  
J M Ball ◽  
J B Hnatiw
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Nuclear Reactor ◽  
Ph Dependence ◽  
Radiolysis Product ◽  
Molecular Iodine ◽  
Water Radiolysis ◽  
Reactor Accident ◽  
Rate Law ◽  
Accident Conditions

The reduction of I2 by hydrogen peroxide, a primary water radiolysis product, has been identified as a key reaction that would influence iodine volatility in nuclear reactor accident conditions (1–3). Although there have been a number of studies of the reduction of I2, there exists a great degree of controversy regarding the intermediates involved, the effect of buffers, and the general rate law (1–9). Because the rates and the mechanism of this reaction are important in predicting the pH dependence of iodine behaviour in reactor containment building after a postulated reactor accident, we have undertaken a kinetic study of I2 reduction by H2O2 in aqueous solution over a pH range of 6–9. The experiments were performed using stopped-flow instrumentation and monitoring the decay of I–3 spectrophotometrically. The effects of buffer catalysis have been examined by comparison of kinetic data obtained in sodium barbital (5,5-diethylbarbituric acid), disodium citrate, and disodium hydrogen phosphate buffers. The effect of buffers, combined with the complex acid dependence of the rate law, explains many of the discrepancies reported in earlier literature.Key words: hydrogen peroxide, molecular iodine, kinetics, iodine volatility.

Nitroalkanes as Reductive Substrates for Flavoprotein Oxidases

1972 ◽  
Vol 27 (9) ◽  
pp. 1052-1053 ◽  
Author(s):  
David J. T. Porter ◽  
Judith G. Voet ◽  
Harold J. Bright
Keyword(s):  
Hydrogen Peroxide ◽  
Amino Acid ◽  
Glucose Oxidase ◽  
Ph Dependence ◽  
Kinetic Mechanism ◽  
Acid Oxidase ◽  
Amino Acid Oxidase ◽  
Kinetics Of ◽  
Oxidase Reaction ◽  
Detailed Kinetic Mechanism

Nitroalkanes have been found to be general reductive substrates for D-amino acid oxidase, glucose oxidase and L-amino acid oxidase. These enzymes show different specificities for the structure of the nitroalkane substrate.The stoichiometry of the D-amino acid oxidase reaction is straightforward, consisting of the production of one mole each of aldehyde, nitrite and hydrogen peroxide for each mole of nitroalkane and oxygen consumed. The stoichiometry of the glucose oxidase reaction is more complex in that less than one mole of hydrogen peroxide and nitrite is produced and nitrate and traces of 1-dinitroalkane are formed.The kinetics of nitroalkane oxidation show that the nitroalkane anion is much more reactive in reducing the flavin than is the neutral substrate. The pH dependence of flavin reduction strongly suggests that proton abstraction is a necessary event in catalysis. A detailed kinetic mechanism is presented for the oxidation of nitroethane by glucose.It has been possible to trap a form of modified flavin in the reaction of D-amino acid oxidase with nitromethane from which oxidized FAD can be regenerated in aqueous solution in the presence of oxygen.

Photochemical redox reactions at the zinc oxide-water interface in additive-free systems

1971 ◽  
Vol 24 (6) ◽  
pp. 1193 ◽  
Author(s):  
DR Dixon ◽  
TW Healy
Keyword(s):  
Hydrogen Peroxide ◽  
Redox Reactions ◽  
Heterogeneous Reaction ◽  
Ph Dependence ◽  
H2o2 Production ◽  
Water Interface ◽  
General Reaction ◽  
Interstitial Zinc ◽  
Different Gases ◽  
Hydrolysis Of

When aqueous ZnO suspensions, saturated with oxygen, are irradiated with u.v. light, hydrogen peroxide is formed and a decrease in pH is observed. The effects of different gases (O2, N2, and N2O) on the course of this heterogeneous reaction and also the pH dependence of the reaction have been examined. On the basis of the results obtained, the mechanism which had been previously suggested was modified to allow for the hydrolysis of the zinc(II) ions removed from the crystal lattice during irradiation. A general reaction mechanism proposed to account for H2O2 production in systems with various additives present is extended to additive-free systems where interstitial zinc (Zn1+) is the effective reductant.

Colorimetry of hemoglobin in plasma with 2,2'-azino-di(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS).

1984 ◽  
Vol 30 (3) ◽  
pp. 357-359 ◽  
Author(s):  
M Takayanagi ◽  
T Yashiro
Keyword(s):  
Hydrogen Peroxide ◽  
Calibration Curve ◽  
Plasma Proteins ◽  
Sulfonic Acid ◽  
Minimum Detectable Concentration ◽  
Colored Form ◽  
Analytical Recovery ◽  
Detectable Concentration ◽  
Precision And Accuracy

Abstract Hemoglobin in plasma can be determined by the color-developing action of 2,2'-azino-di(3-ethylbenzthiazoline-6-sulfonic acid), which is oxidized to a colored form by a peroxidase-like effect of hemoglobin in the presence of hydrogen peroxide. Sensitivity, precision, and accuracy are discussed. The calibration curve is linear for hemoglobin concentrations up to 1 g/L; the minimum detectable concentration is 20 mg/L. The within-run precision (CV) was 2.39%, analytical recovery 101.8%. Interference from plasma proteins and lipids was eliminated by centrifuging the reaction mixture before measuring its absorbance at 410 nm.

The reaction of 2,4,6-trinitrobenzene sulfonic acid with pancreatic elastase

1970 ◽  
Vol 48 (11) ◽  
pp. 1249-1259 ◽  
Author(s):  
Leticia Rao ◽  
T. Hofmann
Keyword(s):  
Rate Constant ◽  
Sulfonic Acid ◽  
Ph Dependence ◽  
Order Rate Constant ◽  
Trinitrobenzene Sulfonic Acid ◽  
Amino Group ◽  
Tyrosine Residues ◽  
Inactivation Rate Constant ◽  
Lysine Residues ◽  
Ph Range

The reaction of elastase with trinitrobenzene sulfonic acid was investigated in the pH range 9–12. Elastase was found to be inactivated by 2,4,6-trinitrobenzene sulfonic acid. The pH dependence of the pseudo first-order inactivation rate constant showed a pK of 10.3 and gave a Hill plot coefficient of 1.15. Trinitrophenol did not inactivate the enzyme. These results indicate that the inactivation is due to the covalent reaction of trinitrobenzene sulfonic acid with a single group in the enzyme. This group is not the N-terminal since the loss of N-terminal valine was considerably slower than the loss of activity at pH 10.5. The inactivation of elastase with 2,4-dinitrofluorobenzene also showed no correlation with the loss of the N-terminal. When the enzyme was exhaustively treated and fully inactivated with trinitrobenzene sulfonic acid at pH 10.5, the N-terminal valine and two out of three lysine residues were trinitrophenylated. No evidence for the loss of histidine was found. One of the tyrosine residues may be trinitrophenylated as judged from the molar extinction of the trinitrophenylated protein, but it has not been possible to isolate a trinitrophenylated tyrosine-containing peptide. The results can be interpreted in one of two ways: (a) trinitrophenylation of a group with a pK of 10.3, not involved in the activity, inactivates because the introduction of the trinitrophenyl residue causes a denaturation of the enzyme; or (b) a group with a pK of 10.3 controls the active conformation of the enzyme. The results do not exclude the possibility that the N-terminal plays an important role in the activity of the enzyme. Below pH 10.5 the reactivity of the N-terminal is low, indicating that it is buried.At pH 9.0 only the ε-amino group of lysine in position 224 reacted with trinitrobenzene sulfonic acid and full activity was retained. The second-order rate constant for the trinitrophenylation of this group was 25 times higher than that of the ε-amino group of the α-N-benzoyllysine.

The effects of ferulic acid on nucleus pulposus cells under hydrogen peroxide-induced oxidative stress

2011 ◽  
Vol 46 (8) ◽  
pp. 1670-1677 ◽  
Author(s):  
Yung-Hsin Cheng ◽  
Shu-Hua Yang ◽  
Kai-Chiang Yang ◽  
Moon-Pei Chen ◽  
Feng-Huei Lin
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Ferulic Acid ◽  
Nucleus Pulposus ◽  
Nucleus Pulposus Cells
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