Oxidation of substituted anilines by horseradish peroxidase compound II

1990 ◽  
Vol 68 (12) ◽  
pp. 2159-2163 ◽  
Author(s):  
Jin Huang ◽  
H. Brian Dunford
Keyword(s):  
Horseradish Peroxidase ◽  
Enzymatic Oxidation ◽  
Hammett Equation ◽  
Substituted Anilines ◽  
Ph Profile ◽  
Kinetics Of Oxidation ◽  
Aniline Oxidation ◽  
The Difference ◽  
Compound Ii ◽  
Kinetics Of

The kinetics of oxidation of eight monosubstituted anilines catalyzed by horseradish peroxidase compound II has been studied at pH 7.00 and 7.60. With p-toluidine the rates of oxidation by compound II have been measured at 21 pH values between 3.60 and 10.25. The rate–pH profile indicates that an acidic form of compound II and the electrically neutral, unprotonated form of p-toluidine are reactive. The correlation of rate constants for the substituted anilines with the substituent constant σ in the Hammett equation suggests that the aromatic amine donates an electron to compound II in the rate-controlling step and loses a proton simultaneously. The value of ρ, the susceptibility factor in the Hammett equation, is −6.0 ± 0.7. The reactivity of anilines with HRP-II observed in this study is lower than that of anilines with HRP-I observed previously, although the value of ρ is the same within experimental error (D. Job and H. B. Dunford. Eur. J. Biochem. 66, 607 (1976)). The difference in reactivity is explained by the relative complexities of the reactions of compounds I and II. Keywords: horseradish peroxidase, peroxidase compound II, aniline oxidation, Hammett correlation, enzymatic oxidation.

Studies on Horseradish Peroxidase. VII. A Kinetic Study of the Oxidation of Iodide by Horseradish Peroxidase Compound II

1971 ◽  
Vol 49 (18) ◽  
pp. 3059-3063 ◽  
Author(s):  
R. Roman ◽  
H. B. Dunford ◽  
M. Evett
Keyword(s):  
Ionic Strength ◽  
Horseradish Peroxidase ◽  
Kinetic Study ◽  
Rate Constant ◽  
Ph Dependence ◽  
Order Rate Constant ◽  
Acid Dissociation ◽  
Ph Range ◽  
Compound Ii ◽  
Kinetics Of

The kinetics of the oxidation of iodide ion by horseradish peroxidase compound II have been studied as a function of pH at 25° and ionic strength of 0.11. The logarithm of the second-order rate constant decreases linearly from 2.3 × 105 to 0.1 M−1 s−1 with increasing pH over the pH range 2.7 to 9.0. The pH dependence of the reaction is explained in terms of an acid dissociation outside the pH range of the study.

Studies on Horseradish Peroxidase. XII. A Kinetic Study of the Oxidation of Sulfite and Nitrite by Compounds I and II

1973 ◽  
Vol 51 (4) ◽  
pp. 588-596 ◽  
Author(s):  
R. Roman ◽  
H. B. Dunford
Keyword(s):  
Horseradish Peroxidase ◽  
Ground State ◽  
Ph Dependence ◽  
Intermediate Formation ◽  
Ion Concentration ◽  
Compound I ◽  
Hydrogen Ion Concentration ◽  
Ph Range ◽  
Compound Ii ◽  
Kinetics Of

The kinetics of the oxidation of sulfite and nitrite by horseradish peroxidase compounds I and II have been studied as a function of pH at 25° and ionic strength 0.11. The pH dependence of the rate of the reaction between compound I and sulfite over the pH range 2–7 is interpreted in terms of two ground state enzyme dissociations with pka values of 5.1 and 3.3, and that for the compound II reaction with sulfite in terms of a single ground state enzyme dissociation with a pKa value of 3.9. Whereas the reaction between compound I and sulfite produces the native enzyme without the intermediate formation of compound II, the reaction of compound I with nitrite yields compound II. The second-order rate constants for the reactions of compounds I and II with nitrite increase linearly with increasing hydrogen ion concentration over the pH range 6–8.

Studies on Horseradish Peroxidase. XI. On the Nature of Compounds I and II as Determined from the Kinetics of the Oxidation of Ferrocyanide

1973 ◽  
Vol 51 (4) ◽  
pp. 582-587 ◽  
Author(s):  
M. L. Cotton ◽  
H. B. Dunford
Keyword(s):  
Horseradish Peroxidase ◽  
Rate Constant ◽  
Active Sites ◽  
Ph Dependence ◽  
Order Rate Constant ◽  
Second Order ◽  
Compound I ◽  
Order Rate ◽  
Compound Ii ◽  
Kinetics Of

In order to investigate the nature of compounds I and II of horseradish peroxidase, the kinetics were studied of ferrocyanide oxidation catalyzed by these compounds which were prepared from three different oxidizing agents. The pH dependence of the apparent second-order rate constant for ferrocyanide oxidation by compound I, prepared from ethyl hydroperoxide and m-chloroperbenzoic acid, was interpreted in terms of an ionization on the enzyme with a pKa = 5.3, identical to that reported previously for hydrogen peroxide. The second-order rate constant for the compound II-ferrocyanide reaction also showed the same pH dependence for the three oxidizing substrates. However, with more accurate results, the compound II-ferrocyanide reaction was reinterpreted in terms of a single ionization with pKa = 8.5. The same dependence of ferrocyanide oxidation on pH suggests structurally identical active sites for compounds I and II prepared from the three different oxidizing substrates.

On the Low-Temperature Oxidation of Processed Peat

1997 ◽  
Vol 15 (2) ◽  
pp. 162-171 ◽  
Author(s):  
J.C. Jones
Keyword(s):  
Low Temperature ◽  
Low Temperature Oxidation ◽  
Temperature Oxidation ◽  
Kinetics Of Oxidation ◽  
The Difference ◽  
Kinetics Of

Small amounts of processed peat have been examined in a microcalorimeter. Kinetics of oxidation are different from those previously re ported for the same material using much larger samples. The difference is at least in part due to loss of volatiles during the initial conditioning of a sample in the microcalorimeter.

scholarly journals Kinetics of the reaction of compound II of horseradish peroxidase with hydrogen peroxide to form compound III

1989 ◽  
Vol 186 (3) ◽  
pp. 571-576 ◽  
Author(s):  
Suara A. ADEDIRAN ◽  
Anne-Marie LAMBEIR
Keyword(s):  
Hydrogen Peroxide ◽  
Horseradish Peroxidase ◽  
Form Compound ◽  
Compound Ii ◽  
Kinetics Of

ChemInform Abstract: KINETICS OF OXIDATION OF ANILINE AND SUBSTITUTED ANILINES BY PERIODATE

1979 ◽  
Vol 10 (38) ◽  
Author(s):  
M. P. RAO ◽  
B. SETHURAM ◽  
T. N. RAO
Keyword(s):  
Substituted Anilines ◽  
Kinetics Of Oxidation ◽  
Kinetics Of

Horseradish peroxidase. XLII. Oxidations of L-tyrosine and 3,5-diiodo-L-tyrosine by compound II

1980 ◽  
Vol 58 (11) ◽  
pp. 1270-1276 ◽  
Author(s):  
Isobel M. Ralston ◽  
H. Brian Dunford
Keyword(s):  
Horseradish Peroxidase ◽  
Reaction Rate ◽  
Acid Group ◽  
Amino Groups ◽  
Compound I ◽  
Ph Profile ◽  
Rate Versus ◽  
Phenolic Group ◽  
Ph Range ◽  
Compound Ii

The oxidations of both L-tyrosine and 3,5-diiodo-L-tyrosine by compound II of horseradish peroxidase were studied over the pH range of approximately 3 to 10 at 25 °C and at a constant ionic strength of 0.11. The rate versus pH profile for the tyrosine – compound II reaction illustrates the influences of at least two acid group ionizations. An enzyme dissociation (pKa ~ 6.2) has a small effect on the reaction rate; whereas, a second pKa of 9.2, which may be attributed to either the enzyme or substrate, has a greater influence on the rate. The oxidation of tyrosine by compound II is fastest at pH 7.6. In the case of the diiodotyrosine – compound II reaction, three acid dissociations are necessary to describe the plot of log (kapp) versus pH. These include two enzyme pKa values of 3.6 and 8.6, and one substrate pKa of 6.6. The rate optimum for the reaction occurs at pH 5.2 and deprotonation of the phenolic group of diiodotyrosine results in a dramatic decrease in kapp. Diiodotyrosine is required in only a 0.5 M equivalent for the conversion of horseradish peroxidase compound I to compound II. The diiodotyrosine pKa values were estimated as 6.4 and 9.4 for the phenolic and amino groups, respectively.

Kinetics of the Oxidation of L-Cysteine by trans- and cis-Cobalt(III) and Iron(III) Complexes

2006 ◽  
Vol 61 (11) ◽  
pp. 1346-1350 ◽  
Author(s):  
Hamzeh M. Abdel-Halim ◽  
Adnan S. Abu-Surrah ◽  
Hutaf M. Baker
Keyword(s):  
Transition Metal ◽  
Rate Constants ◽  
Metal Ion ◽  
Oxidation Process ◽  
Geometrical Isomers ◽  
Kinetics Of Oxidation ◽  
The Difference ◽  
Kinetics Of ◽  
Solution Kinetics ◽  
Cis Isomer

Kinetics of oxidation of L-cysteine by pairs of trans and racemic cis isomers of cobalt(III) and iron(III) based transition metal complexes have been studied in aqueous solution. Kinetics measurements were run under pseudo first order conditions in which the concentration of cysteine is between one and two orders of magnitude greater than that of the isomers of the transition metal complex. The orders of the reaction with respect to both cysteine and the isomer were determined. The observed rate constants and the overall rate constants of the oxidation process were measured. For all geometrical isomers, it was found that the rate constant of oxidation of L-cysteine by the trans isomer is between one to three orders of magnitude greater than that by the cis isomer. The difference in rates can be explained by a geometric factor around the metal ion center in the complex. The less crowded isomer (trans) makes electron transfer easier and hence facilitates the oxidation process which leads to a higher oxidation rate.

Kinetics and mechanism of the oxidation of mercury by peroxidase

1985 ◽  
Vol 63 (11) ◽  
pp. 2940-2944 ◽  
Author(s):  
Donald C. Wigfield ◽  
Season Tse
Keyword(s):  
Hydrogen Peroxide ◽  
Electron Transfer ◽  
Horseradish Peroxidase ◽  
Rate Constant ◽  
Order Rate Constant ◽  
Kinetics And Mechanism ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Iron Heme ◽  
Kinetics Of

The kinetics of oxidation of zero-valent mercury by the horseradish peroxidase system are reported. The reaction is first order in mercury and first order in peroxidase compound 1, and appear to obey these kinetics to completion of the reaction. The second order rate constant is 8.58 × 105 M−1 min−1 at 23 °C. The data are consistent with a simple two-electron transfer from mercury to the iron–heme system of peroxidase with the enzyme acting as a chemical oxidant that is continually being regenerated by reaction with hydrogen peroxide.

ChemInform Abstract: Oxidation of Substituted Anilines by Horseradish Peroxidase Compound II

ChemInform ◽  
2010 ◽  
Vol 22 (28) ◽  
pp. no-no
Author(s):  
J. HUANG ◽  
H. B. DUNFORD
Keyword(s):  
Horseradish Peroxidase ◽  
Substituted Anilines ◽  
Compound Ii
Sign in / Sign up

Export Citation Format

Share Document