The use of nonaqueous media To probe biochemically significant enzyme intermediates: The generation and stabilization of horseradish peroxidase compound II in neat benzene solution at room temperature

1995 ◽  
Vol 117 (8) ◽  
pp. 2141-2146 ◽  
Author(s):  
Patricia Ann Mabrouk
Keyword(s):  
Horseradish Peroxidase ◽  
Room Temperature ◽  
Benzene Solution ◽  
Nonaqueous Media ◽  
Enzyme Intermediates ◽  
Compound Ii

Horseradish peroxidase. XXXIV. Oxidation of compound II to I by periodate and inorganic anion radicals

1979 ◽  
Vol 57 (8) ◽  
pp. 1080-1083 ◽  
Author(s):  
A. Nadezhdin ◽  
H. B. Dunford
Keyword(s):  
Horseradish Peroxidase ◽  
Ultraviolet Light ◽  
Room Temperature ◽  
Sodium Periodate ◽  
Compound I ◽  
Inorganic Anion ◽  
Temperature Irradiation ◽  
The One ◽  
Compound Ii ◽  
Anion Radicals

The one-electron oxidation of horseradish peroxidase compound II to compound I by sodium periodate was observed. The bimolecular rate constant for the NaIO4–compound II interaction is equal to 9.5 ± 1 × 10−3 M−1 s−1 at room temperature. Irradiation, using ultraviolet light, of the solution containing compound II and persulfate in the presence of bicarbonate, chloride, or bromide, leads to the fast accumulation of compound I due to the oxidative action of [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] anion radicals, which are products of the photolysis.

Kinetic studies on the oxidation of phenols by the horseradish peroxidase compound II

1997 ◽  
Vol 1339 (1) ◽  
pp. 79-87 ◽  
Author(s):  
Prasanta K. Patel ◽  
Madhu Sudan Mondal ◽  
Sandeep Modi ◽  
Digambar V. Behere
Keyword(s):  
Horseradish Peroxidase ◽  
Kinetic Studies ◽  
Oxidation Of Phenols ◽  
Compound Ii

Rate constants for reactions of horseradish peroxidase compounds I and II with 4-substituted arylboronic acids

1994 ◽  
Vol 72 (10) ◽  
pp. 2159-2162 ◽  
Author(s):  
Weimei Sun ◽  
Xiaoying Ji ◽  
Larry J. Kricka ◽  
H. Brian Dunford
Keyword(s):  
Horseradish Peroxidase ◽  
Rate Constants ◽  
Compound I ◽  
Arylboronic Acid ◽  
Experimental Conditions ◽  
Kinetic Measurements ◽  
Arylboronic Acids ◽  
Total Ionic Strength ◽  
Compound Ii ◽  
Catalyzed Oxidation

The rate constants for the reactions of horseradish peroxidase compound I (k1) and compound II (k2) with three 4-substituted arylboronic acids, which enhance chemiluminescence in the horseradish peroxidase catalyzed oxidation of luminol by hydrogen peroxide, were determined at pH 8.6, total ionic strength 0.11 M, using stopped-flow kinetic measurements. For comparison, the rate constants of the reactions of 4-iodophenol with compounds I and II were also determined under the same experimental conditions. The three arylboronic acid derivatives and their rate constants are: 4-biphenylboronic acid, k1 = (1.21 ± 0.08) × 106 M−1 s−1, k2 = (4.6 ± 0.2) × 105 M−1 s−1; 4-bromophenylboronic acid, k1 = (5.5 ± 0.2) × 104 M−1 s−1, k2 = (3.6 ± 0.2) × 104 M−1 s−1; and 4-iodophenylboronic acid, k1 = (1.1 ± 0.2) × 105 M−1 s−1, k2 = (1.3 ± 0.1) × 104 M−1 s−1. 4-Biphenylboronic acid, which shows comparable luminescent enhancement to 4-iodophenol, has the highest reactivity in the reduction of both compounds I and II among the three arylboronic acid derivatives tested.

Kinetic and molecular orbital studies on the rate of oxidation of monosubstituted phenols and anilines by horseradish peroxidase compound II

Biochemistry ◽  
1990 ◽  
Vol 29 (17) ◽  
pp. 4093-4098 ◽  
Author(s):  
Junji Sakurada ◽  
Reiko Sekiguchi ◽  
Koichi Sato ◽  
Toichiro Hosoya
Keyword(s):  
Horseradish Peroxidase ◽  
Molecular Orbital ◽  
Compound Ii

Article

1999 ◽  
Vol 77 (5-6) ◽  
pp. 1066-1076
Author(s):  
Hideo Tomioka ◽  
Junichi Nakajima ◽  
Hidehiko Mizuno ◽  
Eiji Iiba ◽  
Katsuyuki Hirai
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Room Temperature ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Benzene Solution ◽  
Laser Flash ◽  
Spin Resonance ◽  
Structure Reactivity Relationship ◽  
Resonance Laser

A series of triplet 9-triptycyl(aryl)carbenes, where aryl groups are phenyl, 1- and 2-naphthyl, and 9-anthryl, is generated by photolysis of the corresponding diazomethanes and observed directly by spectroscopic means. Their structures are characterized by electron spin resonance (ESR) spectroscopy in a 2-methyltetrahydrofuran matrix at 77 K, and the reactivities are investigated by laser flash photolysis in degassed benzene solution at room temperature. Comparison of the data with other arylcarbenes bearing a series of substituents, i.e., hydrogen, phenyl, naphthyl, and anthryl groups, revealed an interesting relationship between structures and reactivities of triplet arylcarbenes.Key words: steric protection, stability of triplet carbenes, electron spin resonance, laser flash photolysis, structure-reactivity relationship.

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.

Magnetism, electronic spectra, and structure of transition metal alkoxides. II. The preparation and magnetism of iron(III) alkoxides

1966 ◽  
Vol 19 (3) ◽  
pp. 363 ◽  
Author(s):  
RW Adams ◽  
RL Martin ◽  
G Winter
Keyword(s):  
Room Temperature ◽  
Benzene Solution ◽  
Magnetic Moments ◽  
Exchange Interactions ◽  
Metal Alkoxides ◽  
Antiferromagnetic Exchange ◽  
Crystal Data ◽  
Magnetic Susceptibilities ◽  
X Ray ◽  
The Core

The iron(III) alkoxides, Fe(OMe)3, Fe(OEt)3, and Fe(Obun)a have been prepared by a procedure alternative to those previously described in the literature. The trimeric nature of the three compounds in benzene is confirmed by cryoscopy, and preliminary X-ray single crystal data for the ethoxide are consistent with trimeric entities in the solid. The temperature variation of the magnetic susceptibilities for the three compounds follows the Curie-Weiss law between 90 and 300�K but with large values of θ=- 200�K. The unusually low magnetic moments vary markedly with temperature, and at room temperature remain depressed in benzene solution at peer μeff 4.4 B.M. This anomalous behaviour is ascribed to the presence of weak antiferromagnetic exchange interactions within the cluster of iron atoms which forms the core of the trimeric species Fe3(0R)9. The compounds are sensitive both to hydrolysis and to heating. Hydrolysis decreases and pyrolysis increases the magnetic susceptibility. This provides a convenient method for following the progress of both types of reaction.

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